Get an external event's payload

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

The readOnlyHint annotation already establishes this as a safe read, so the description's burden is lighter; it still adds real value by disclosing that the payload can expire and then returns 410. It says nothing about permission requirements or payload size, but the expiry disclosure is a meaningful trait not present in the annotations.

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 resource and its scoping constraint front-loaded and the error behavior appended. 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-shape detail is unnecessary; the description covers purpose, the precondition for a valid call, and the notable failure mode. For a single-row read with a fully documented schema and annotations, nothing material is missing.

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 coverage is 100%, so the baseline is 3, but the description adds semantics for incident_event_id by narrowing it to rows where hasExternalEvent is true, which the schema's terse 'Timeline row ID.' does not convey. The account-override parameter is left to the schema, which documents it thoroughly.

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 states a specific verb (fetch) and resource (the raw JSON an external system sent) scoped to exactly one row of an incident timeline, and adds the discriminator 'a row whose hasExternalEvent is true'. This lets an agent distinguish it from list_incident_events or get_incident without opening a schema.

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?

It gives a concrete pre-condition for use (the timeline row must have hasExternalEvent true) and states the failure case (410 after expiry), which is clear operational context. It does not, however, name an alternative tool or say what to do when the row lacks an external event, so it stops short of explicit when-not guidance.

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