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

Annotations already cover the safety profile (readOnly, idempotent, closed-world, non-destructive), and the description still adds real value: the required 'email:read' scope, the exact returned fields (mailbox_id, message_id, event status, legacy decision/reason), and the subtle clarification that a legacy decision is not this connection's completion. That last point prevents a genuine misreading of the result.

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?

Front-loads purpose, then prerequisites, then alternatives/exclusions in three tight sentences with no filler. Every clause carries routing or safety information, including the dense final sentence about decision semantics.

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 one-parameter read with no output schema, the description compensates by enumerating the return fields and stating auth requirements. Combined with rich annotations and full schema coverage, an agent has everything needed to call this correctly and interpret the result.

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%, and the schema already explains that event_id comes from list_email_events or claim_email_batch and is not a message ID. The description adds no parameter-level syntax or formatting detail beyond that, so the baseline 3 is correct.

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?

States a specific verb and resource ('Inspect one authorized event's metadata') and immediately scopes it with 'when its message body is not needed,' which cleanly separates it from read_email and get_email_context. The sibling list confirms those alternatives exist and the description names one of them directly.

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?

Gives an explicit when ('metadata ... when message body is not needed'), a named alternative ('Use get_email_context to read both the event and email'), and negative routing ('Does not save processing progress, change source mail or send notifications'), which steers the agent away from report_email_decision and send_email. Nothing is left to inference.

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