API quota usage

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable behavioral detail: 'Daily counters reset at 12:00 UTC — midday, not midnight.' This clarifies a potentially confusing aspect beyond what annotations provide. No contradiction with annotations.

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 two sentences with no filler. The first sentence front-loads the core purpose and output shape, while the second adds the critical reset-time detail and the diagnostic use case. Every phrase contributes value, and it is appropriately sized for the tool's complexity.

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?

There is no output schema, but the description compensates by explicitly listing the output fields (quotaGroups[] with name, quotaUsage, quotaLimit, quotaMinuteLimit, methodDetails[]). It also covers the daily reset behavior and the primary use case (429 errors, headroom). For a read-only diagnostic tool, this is complete and well-rounded.

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 parameters (account, page_size, page_token) are fully documented in the schema. The description does not add parameter-specific guidance beyond the schema, but it does describe the output structure (quotaGroups, methodDetails) which indirectly relates to how parameters affect results. Baseline 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 begins with 'Shows the account's Merchant API usage vs limits per method group', clearly identifying the verb (shows), resource (Merchant API quota usage), and scope (per method group). It distinguishes from sibling tools like list_products or list_promotions by focusing on quota diagnostics and explicitly mentions the quota sub-API.

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 provides clear context by stating 'Use it to diagnose HTTP 429 RESOURCE_EXHAUSTED errors and to see how much headroom is left.' This gives a specific use case, but it does not explicitly mention when not to use it or name alternative tools, so it stops short of a 5.

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