Get an external event's payload

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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds real behavioral value beyond that by disclosing that the payload expires and that the tool returns 410 afterward, which an agent needs to interpret failures correctly. Auth/account semantics are handled in the schema rather than here.

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 sentences, zero filler, with the key scoping constraint front-loaded and the expiry caveat immediately after. Every clause earns its place.

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?

An output schema exists, so return-value details need not be described, and the 410/expiry caveat covers the main edge case. Combined with the schema and annotations, an agent has what it needs to call this correctly.

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%, including a detailed explanation of the account-override header, so the schema carries the parameter burden and the baseline is 3. The description's mention of externalEventPath adds context about which event id is valid but no syntax or format detail 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 (fetch) and a precisely scoped resource (the raw JSON an external system sent for one incident timeline row). The qualifier 'a row whose externalEventPath is set' distinguishes it cleanly from the sibling list_incident_events, so the purpose is unambiguous.

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 tells the agent the precondition for calling it - the timeline row must have externalEventPath set - which is effective routing guidance. It does not explicitly name an alternative tool or state when not to use it, so it falls 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.