count_emails

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

No annotations are provided, so the description bears full responsibility. It notes that messages are counted 'without fetching full envelopes,' indicating lightweight read behavior, but does not disclose other behavioral traits such as rate limits, authentication needs, or response format beyond the 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 two sentences, front-loaded with the key action and scope. Every sentence adds value with no redundancy.

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 simple counter tool with an output schema, the description covers the primary purpose and a behavioral restraint (no envelope fetching). However, it omits usage guidance and parameter hints, but given the tool's simplicity, it is largely sufficient.

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 0% and the description adds no parameter-level information. With 7 parameters, the description should compensate but does not, leaving the AI agent to rely solely on parameter titles, which are minimally descriptive.

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 explicitly states 'Count messages matching filters without fetching full envelopes' and gives a concrete example ('how many emails from Amazon this month?'), making the tool's purpose very clear and distinguishing it from sibling tools like list_emails or count_unread.

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 a general counter example but does not explicitly state when to use versus alternatives like count_unread or search_emails_by_sender. Usage is implied rather than explicit.

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