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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds the useful auth requirement ('Authorization Bearer read token header'), which annotations do not convey, but says nothing about behavior when the id does not exist or what is returned.

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?

Two short, front-loaded sentences with no filler: purpose first, then auth. The telegraphic 'Auth:' fragment is compact rather than wasteful.

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 two-parameter read tool with rich annotations and no output schema, the definition covers purpose and the non-obvious auth requirement. The only real gap is the shape of the returned event, which is not described anywhere.

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 both inbox_id and event_id are documented in the schema and the baseline is 3. The description's 'by id' touches only event_id and does not mention that inbox_id is also required to scope the lookup, adding little meaning beyond the schema.

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 ('Get one event by id'), which contrasts implicitly with the sibling list_events (many) and wait_for_event (blocking). It is clear but never names those siblings, so the distinction is left to inference.

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?

Usage is only implied by 'by id' – an agent can infer it is the right tool when it already holds an event id. There is no explicit when-not or pointer to list_events/wait_for_event for discovery or polling cases.

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