Sign-in and quota status

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

The annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is clear. The description adds valuable behavioral context: that it costs no image quota, which is not in annotations. This extra detail helps the agent understand the cost-free nature of the call, but it doesn't describe other behavioral traits like response format, which is acceptable given no output schema.

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?

The description is concise, front-loaded with the core purpose, and includes a clear usage trigger. Every sentence serves a purpose: defining the tool, noting the non-cost, and specifying when to call it. No wasted words.

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 read-only status tool with no required parameters and full schema coverage, the description is complete. It covers what it reports, the absence of quota cost, and when to use it. The output format is not described, but without an output schema, this is acceptable for a simple status check. The tool is simple enough that nothing critical 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 description coverage is 100%, so the schema fully documents the 'check_usage' parameter. The description does not add additional meaning beyond the schema, but it does mention usage-limit windows, which aligns with 'check_usage'. Since the schema is complete, a baseline of 3 is appropriate.

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 clearly states what the tool does: shows sign-in status, account/plan, credential source, and usage-limit windows. It distinguishes itself from siblings like sign_in and generate_image by focusing on status rather than action. However, it could be slightly more specific about the tool's name, but the resource is clear.

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?

The description explicitly tells when to use this tool: when another tool reports an auth or quota problem, or after sign_in. This provides clear context and routes the agent correctly. It also implies when not to use it (e.g., for actual image generation), which is helpful.

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