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Sim MCP

Tools

Discover an operation, inspect its request, and call it with the correct access.

Sim MCP exposes four tools for discovering and calling its supported JSON API operations. Search for an operation, inspect its inputs, then call the read or write tool named in its description.

Tools

ToolDoes
search_operationsFinds operations by keyword ("table rows") or by area (tables, workflows, knowledge, …). Returns each operation's name, method, path, summary, and the tool that runs it.
describe_operationReturns an operation's description and the JSON Schema of its path parameters, query, body, and headers.
call_read_operationRuns an operation that only needs read access, such as listWorkspaces, queryRows, or getWorkflowRun.
call_write_operationRuns an operation that needs write access: one that creates, changes, runs, or deletes something, or reaches out to another service, such as createTable, executeWorkflow, or listMcpServerTools.

The operation's required access determines the tool, rather than its HTTP method: a read can use POST, and a GET that contacts another service can require write access. Your app controls tool approvals.

search_operations returns the total number of matches and at most limit operations: 25 by default, 100 maximum. Catalog search has no cursor. Narrow the keywords or domain when matches exceed that limit; this is separate from paginating API resources.

Calling an operation

Operation names match the CLI and the API reference. A call names the operation and fills the parts of the request it needs:

Code
{
  "operation": "listTableRows",
  "params": { "tableId": "tbl_8f2c" },
  "query": { "workspaceId": "ws_91ab", "limit": 50 }
}
FieldHolds
paramsPath parameters, such as tableId or workflowId
queryQuery-string parameters; most operations need workspaceId
bodyThe JSON request body when the operation declares one, including read operations such as queryRows
headersOnly headers the operation declares, such as upload-token

For example, queryRows uses the read tool with a JSON body:

Code
{
  "operation": "queryRows",
  "params": { "tableId": "tbl_8f2c" },
  "body": { "workspaceId": "ws_91ab", "limit": 50 }
}

Keep authentication in your app's connection configuration. You cannot pass undeclared authentication or protocol headers, including X-API-Key, Authorization, or Accept, through the call's headers field.

Results and errors

The result is the same JSON the API returns, usually { "data": … }. Paginated list operations use limit and cursor; check the operation because some lists do not support pagination. A failed API call returns its error, such as { "error": { "code": "NOT_FOUND", "message": "…" } }, so the agent can correct its request.

Limits

  • Same rules as the API. Permissions, rate limits, and request validation are the API's own; nothing is looser through MCP.
  • 1 MiB per API result. Request smaller pages for paginated lists. A single-resource result may also exceed the limit. The size check happens after the API executes: if a write returns a size error, check the resource state before repeating it because the change may already have succeeded.
  • No streaming. Run a workflow without stream: true to wait for its result, or with async: true and poll getWorkflowRun.
  • No file bytes. Downloads, knowledge base exports, and multipart document uploads are not available over MCP; use the CLI or the API.

Related docs

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