append_values
Appends rows after the last row of the data table that contains the given range — pass the table's region (e.g. "Sheet1!A1:D1" or just "Sheet1") and the API finds the first free row itself; the response's updates.updatedRange shows where the rows actually landed. insert_data_option INSERT_ROWS pu...
This record as markdown: /tools/a1-x-tech-mcp-google-sheets/append-values.md
What append_values does on Mcp Google Sheets
AI agents call append_values to retrieve information from Mcp Google Sheets without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
| Parameter | Type | Required | Description |
|---|---|---|---|
range | string | Yes | A1 range identifying the table to append to (the API scans it for the last data row). |
values | array | Yes | 2-D array of cell values, outer array = rows: [["Name","Score"],["Ada",42]]. null leaves the existing cell untouched. |
spreadsheet_id | string | Yes | The spreadsheet id — the long id from the URL (docs.google.com/spreadsheets/d/<spreadsheetId>/edit) or from create_spreadsheet / search_spreadsheets output. |
insert_data_option | string | — | OVERWRITE writes after the table (default); INSERT_ROWS inserts new rows, shifting data below. |
value_input_option | string | — | USER_ENTERED (default) parses formulas/numbers/dates; RAW stores literal strings. |
Parameters from the server's own tool schema.
Why append_values is rated Low
Even though append_values only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.
Attacks that exploit this kind of access
The rule that runs append_values safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Mcp Google Sheets, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For append_values, this is the rule to start with:
append_values is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Mcp Google Sheets, apply this rule, and every append_values call is checked against it from then on.
Questions about append_values
Appends rows after the last row of the data table that contains the given range — pass the table's region (e.g. "Sheet1!A1:D1" or just "Sheet1") and the API finds the first free row itself; the response's updates.updatedRange shows where the rows actually landed. insert_data_option INSERT_ROWS pushes existing data below down; OVERWRITE (default behaviour) writes into the free rows after the table. Never retried after an ambiguous failure — re-appending would duplicate the rows, so check the sheet first (read_values) before re-sending. It is categorised as a Read tool in the Mcp Google Sheets MCP Server, which means it retrieves data without modifying state.
append_values accepts 5 parameters: range, values, spreadsheet_id, insert_data_option, value_input_option. Required: range, values, spreadsheet_id. The full parameter table on this page comes from the server's own tool schema.
Register the Mcp Google Sheets MCP server in PolicyLayer and add a rule for append_values: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Mcp Google Sheets. Nothing to install.
append_values is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the append_values rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for append_values. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
append_values is provided by the Mcp Google Sheets MCP server (@a1-x-tech/mcp-google-sheets). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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