Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the annotations it discloses the key side effects and constraints: nothing is overwritten, rows are matched by id and mismatched rows are skipped and named, each write appends an audit line to an 'InstaMaps runs' tab, and the target sheet must be shared with the service account as Editor (with an error naming the address otherwise). This is consistent with idempotentHint=false (each write adds a line) and destructiveHint=false.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Purpose is front-loaded in the first clause, but the second sentence is a long run-on packing run_id, job_id, mode behavior, and skip semantics into one block, which makes it harder to scan. It is dense rather than wasteful, so it stays informative.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 6-parameter write tool with no output schema, the description covers the essentials: auth requirement, side effects, row-matching/skip behavior, mode defaults, and audit logging. Nothing critical to invoking it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description adds real meaning: it clarifies the run_id vs job_id decision, that run_id comes from an answer (run.run_id) or get_job, and that mode/columns have defaults. It does not explain the 'tab' or 'sheet' parameters beyond what the schema already says.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb+resource+scope: 'Writes an earlier answer into a Google Sheet without overwriting anything.' No sibling tool (ask_table, render_map, update_map, etc.) writes answer rows to a sheet, so an agent can distinguish it immediately, and the non-overwriting constraint is stated up front.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives clear routing conditions: use run_id to write a finished answer's rows, use job_id to write chunks as a background job finishes or the whole run at completion, and it explains when each mode default applies. There are no true sibling alternatives to name, but no explicit 'when not to use' is offered.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.