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

With no annotations, the description carries the full burden. It discloses key behavioral traits: it's a read-only query, scoped to the calling API key, and limited to the current month. It doesn't mention potential caveats like caching or rate limits, but the core behavior is transparent for a simple query.

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?

A single clean sentence that is front-loaded and provides all necessary information without extraneous 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?

Given the tool's simplicity (no params, no output schema), the description adequately specifies the return content (quota status, recent usage) and scope. It falls short of explaining the exact response structure, but that's acceptable for a basic usage query.

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?

There are no parameters, so baseline is 4. The description doesn't need to explain parameters since none exist, and the schema trivially covers 100%.

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 the tool returns current-month quota status and recent usage for the calling API key, using a specific verb and resource. It distinguishes from siblings (search_leads, validate_lead) which are lead-related, leaving no ambiguity.

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 implies usage context (checking quota/usage for the API key) but does not explicitly state when to choose this tool over alternatives or provide exclusions. Sibling tools are clearly unrelated, so intent is clear, but there's no explicit guidance.

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