Oyster MCP server

Read team, time off, expenses and invoices; approve or decline time off and expenses in Oyster. Hosted by usefulapi: connect it to Claude, ChatGPT, Cursor or any MCP client.

Connect Oyster50 free tool calls a month

What can I ask?

Turn on the Oyster connector, then ask in plain words. The AI picks the tools.

Who is on the team, by country and department?
Which time off requests are waiting, and how many days does each person have left?
Show unreviewed expenses from this month and their totals.
Which Oyster invoices are overdue or waiting for a wire transfer?

What you can do with Oyster in Claude and ChatGPT

For HR and finance teams that run employer-of-record staff, contractors and payroll in Oyster.

Look up the team and its departments

List the team members with their role, type and start date, and list the departments. Open one person for the employment details and benefits. Personal details stay out of the list.

Review the time off requests and balances

List the time off requests that wait for a decision. Check the remaining days of each person in the time off balances.

Approve or reject a time off request

Open a pending time off request to read its dates and reason. Then approve it, or reject it with a reason the team member sees.

Changes data

Review and decide on expenses

List the expenses that wait for review and open one to check its amount and receipt. Then approve it for reimbursement, or decline it with a reason the team member sees.

Changes data

Check the company's Oyster invoices

Filter the company's Oyster invoices by status or charge status. Open one to see its line items, tax and document links.

Find time sheets that wait for approval

List the time sheets with their status to find those that wait for submission or approval. Open one to see the daily entries and time off days.

How do I connect Oyster?

Before you connect

You sign in with your Oyster account and approve the access (OAuth). You do not need an API key.

A Company Admin must approve the access. The server reads your data when you ask, and approves or rejects time off and expenses only when you ask it to. You can remove the access any time in Oyster.

Claude claude.ai · Desktop

Open Customize → Connectors, then click + Add → Add custom connector.
Enter the name Oyster and this URL, then click Add:
https://oyster.usefulapi.io/mcp
Claude opens the Oyster login page: sign in and approve the access.
In a chat, click + → Connectors and turn on Oyster.

Team and Enterprise: an Owner adds the connector for the organization first.

ChatGPT chatgpt.com

Open Plugins, click +, then Add custom MCP server.
Enter the name Oyster and this URL, choose OAuth as the authentication, confirm the warning and create it:
https://oyster.usefulapi.io/mcp
ChatGPT opens the Oyster login page: sign in and approve the access.
In Plugins, install Oyster, then choose it in a chat.

No Add custom MCP server option? It depends on your account or workspace settings: see OpenAI's guide.

Claude Code

Run this command, then run /mcp in Claude Code to log in:

claude mcp add --transport http oyster https://oyster.usefulapi.io/mcp

Cursor

Add to Cursor or add this to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "oyster": {
      "url": "https://oyster.usefulapi.io/mcp"
    }
  }
}

VS Code

Add to VS Code or add this to .vscode/mcp.json:

{
  "servers": {
    "oyster": {
      "type": "http",
      "url": "https://oyster.usefulapi.io/mcp"
    }
  }
}

Codex

Run these commands. The second one opens the login page:

codex mcp add oyster --url https://oyster.usefulapi.io/mcp

codex mcp login oyster

Other clients

Windsurf, Cline, Zed and other MCP clients: add this URL as a remote MCP server (Streamable HTTP). The client then opens the login page in your browser.

https://oyster.usefulapi.io/mcp

Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: you sign in with your Oyster account. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.

Pricing

Plan	Price	Limit
Free	$0	50 tool calls / month
Proper user	$9/mo · $90/yr	10,000 tool calls / month
Pro+per user	$39/mo · $390/yr	100,000 tool calls / month

Each paid plan covers this Oyster server only. Ask your AI to run oyster_upgrade and choose Pro or Pro+, billed monthly or yearly (it returns a Stripe Checkout link). If you already have Pro, ask to change it to Pro+. The change requires your confirmation, keeps your billing interval and charges the price difference for the rest of the period immediately. Cancel any time with oyster_cancel_subscription: your paid plan continues to the end of the paid period, with no refund for the current period, and asking to resume the same plan with oyster_upgrade before then undoes the cancel. Or write to [email protected].

Tools 24

Show all 24 tools (the AI picks them for you)

Read only · 16

Get companyoyster_get_company
The connected Oyster company: id, name, registration number and corporate/billing addresses.
List team membersoyster_list_team_members
List the company's team members (Oyster engagements: EOR employees, contractors, payroll team members) with name, role, type, state, country, start date, department and work email. Private details (date of birth, addresses, phones, salary, tax id) are left out; use oyster_get_team_member for one person.
Get team memberoyster_get_team_member
One team member (engagement) with employment or contract details, department, benefits and terminations. Salary only with include_compensation; date of birth, addresses, phone numbers and citizenships only with include_personal_details. A contractor's tax id is never returned.
List departmentsoyster_list_departments
List the company's departments with their description and number of team members.
List time off requestsoyster_list_time_off_requests
List time off requests with person, dates, type, state, reason and comments, optionally for some team members only.
Get time off requestoyster_get_time_off_request
One time off request with dates, day durations, hours, state, type, reason, comments and attachment.
List time off balancesoyster_list_time_off_balances
Time off entitlements per team member, in days: annual entitlement, accrued, carried over, adjusted, taken, available, upcoming and projected balance.
List public holidaysoyster_list_public_holidays
Public holidays between two dates (up to two years ahead) for a country (ISO code, optional subdivision) or for a team member's location.
List expensesoyster_list_expenses
List team members' expenses with amount, category, dates, review state (UNREVIEWED, APPROVED, DECLINED) and receipt link. Search by name and filter by review state.
Get expenseoyster_get_expense
One expense with amount, receipt amount, category, dates, review state, receipt link and team member.
List contract changesoyster_list_contract_changes
List contract change requests for all team members (position, compensation, bonus, allowance changes) with state, effective date, requester and the changes.
Get contract changeoyster_get_contract_change
One contract change with the requested changes, state, dates, team member and amendment documents.
List invoicesoyster_list_invoices
List the company's Oyster invoices with type, status, payroll month, issue and due dates, amount, charge (payment) status and payout status. Filter by payroll period, issue date, type, status, charge status or team member.
Get invoiceoyster_get_invoice
One invoice by ID or reference code, with line items, tax, applied credit, charge, payout and document links.
List time sheetsoyster_list_time_sheets
List time sheets with team member, period, cadence, status (PENDING_SUBMISSION, SUBMITTED, PENDING_APPROVAL, APPROVED) and worked/time-off totals.
Get time sheetoyster_get_time_sheet
One time sheet with totals, work summary, time off days and the daily entries.

Changes data · 4

Approve time off requestoyster_approve_time_off_request
WRITE: approve a pending time off request. Only on the user's explicit request; check the request with oyster_get_time_off_request first. Needs the manage scope.
Reject time off requestoyster_reject_time_off_request
WRITE: reject a pending time off request with a reason the team member sees. Only on the user's explicit request. Needs the manage scope.
Approve expenseoyster_approve_expense
WRITE: approve an unreviewed expense for reimbursement. Only on the user's explicit request; check it with oyster_get_expense first. Needs the manage scope.
Decline expenseoyster_decline_expense
WRITE: decline an unreviewed expense, optionally with a reason the team member sees. Only on the user's explicit request. Needs the manage scope.

Your usefulapi plan · 4

Usage status (free-tier meter)oyster_usage_status
Report the caller's current usage: the plan, calls used this month, the limit of the plan (the free monthly cap or the Pro fair use limit), remaining, and whether the limit is reached. Read-only; does not count against the meter.
Request a missing featureoyster_request_feature
Tell usefulapi that the user needs something the Oyster tools cannot do yet (a missing tool, field or filter). Call it only when the user asks for something none of the tools can do, and tell the user that you send the request. Do not call it for errors or for normal requests. Do not include personal data, credentials or customer records. Stored with the product name and the client type (for example Claude or Cursor), without the user's account. At most 5 requests per day. Does not count against the meter.
Upgrade to Pro or Pro+oyster_upgrade
Get a paid plan for Oyster (the free tier caps monthly usage). Pro: 10,000 tool calls a month, for normal use — plan "monthly" ($9/month) or "yearly" ($90/year, 2 months free). Pro+: 100,000 tool calls a month, for automations and heavy use — plan "plus" ($39/month) or "plus_yearly" ($390/year). Without a plan it returns both Pro and Pro+, each with a payment link, for the user to choose; with a plan, one link. An existing Pro subscription changes to Pro+ in place: call without confirm first, as the reply states the exact charge for this account (the price difference for the rest of the period, or in a free Pro trial the full Pro+ price, as the trial ends); then call with confirm: true. Cancel any time: the plan then runs to the end of the paid period, so it also suits a one-time job. A link opens Stripe Checkout in the browser; after payment the account upgrades automatically. Does not count against the meter.
Cancel the Pro subscriptionoyster_cancel_subscription
Cancel the caller's Oyster Pro subscription at the end of the paid period (no refund for the current period; Pro continues until then, then the free tier applies). Requires confirm: true. Run oyster_upgrade later to undo the cancel before the period ends. Does not count against the meter.

FAQ

What can I do with Oyster in Claude or ChatGPT?

Look up the team and its departments. Review the time off requests and balances. Approve or reject a time off request. Review and decide on expenses. Check the company's Oyster invoices. Find time sheets that wait for approval. See what you can do for the details.

Is this an official Oyster product?

No. usefulapi is an independent service. It is not affiliated with or endorsed by Oyster. The server calls the Oyster API with your own Oyster access, so it sees only the data that your account can see.

Can I connect Oyster to Claude or ChatGPT?

Yes. In Claude, add this server's URL as a custom connector. In ChatGPT, add it as a custom MCP server in Plugins. Then log in once. Cursor, VS Code, Claude Code and Codex work too. See the setup steps.

What do I need to connect?

A Oyster account. You sign in to Oyster and approve the access. You do not need an API key.

Do I add an Authorization header to the client config?

No. Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: you sign in with your Oyster account. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.

How do you keep my Oyster credentials?

The login stores them encrypted in the authorization grant of your connection. The server uses them to call the Oyster API for you and to derive a private account id for usage metering. usefulapi does not show them on any page or in any reply. You can revoke the access in Oyster at any time.

Can the AI change my Oyster data?

Yes, if you approve it. 4 of the 20 Oyster tools can create or change data. The other 16 are marked read-only. Most MCP clients ask you to approve a tool call before it runs.

What does it cost?

The Free plan gives 50 tool calls / month. Pro costs $9/mo or $90/yr, with 10,000 tool calls / month. Pro+ costs $39/mo or $390/yr, with 100,000 tool calls / month. Each subscription covers this Oyster server only. Cancel any time: your paid plan then runs to the end of the paid period. Run oyster_usage_status to see how many calls you used.

How do I subscribe or cancel?

Ask the AI to run oyster_upgrade and choose Pro or Pro+, billed monthly or yearly: it returns a Stripe Checkout link. If you already have Pro, ask to change it to Pro+. After you confirm, your existing subscription changes in place, keeps its billing interval and charges the price difference for the rest of the period immediately. To cancel, run oyster_cancel_subscription. Your paid plan continues to the end of the paid period.

What if a Oyster tool that I need is missing?

Tell the AI what you wanted to do. It can send the request with oyster_request_feature. We store the text with the server name, the type of AI client and the tool you tried, not with your account, and read every request when we plan new tools. You can send up to 5 requests per day.

Which AI clients can I use?

Any client that supports remote MCP servers (Streamable HTTP) with OAuth login: Claude (web and desktop), Claude Code, ChatGPT, Codex, Cursor, VS Code, Windsurf and others.

This is a Model Context Protocol endpoint — meant to be connected from an AI client, not opened in a browser. An invalid_token response at the URL is the auth gate working as designed; clients authenticate automatically.

Need a tool this server does not have, or a connection to another system? We build custom integrations and MCP servers.

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