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

Annotations already fully cover the safety profile (readOnlyHint, idempotentHint, openWorldHint=false, destructiveHint=false), lowering the bar. The description still adds a lifecycle nuance beyond the annotations: the agent's final reply is only present once the run has settled, so output is state-dependent. It does not describe error/running states or auth needs, keeping it below a 5.

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?

A single front-loaded sentence that lists the four pieces of returned information with zero filler. Every clause earns its place and nothing is buried.

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?

With an output schema present, return values need not be re-explained, annotations cover safety, and the lone parameter is fully documented in the schema. The description is therefore functionally complete; the only remaining gap is the missing routing guidance relative to wait_for_run and list_runs.

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% for the single run_id parameter (documented as 'trun_...'), so the schema carries the meaning. The description only implies that a run is identified by an id and adds no format or constraint detail beyond the schema, making the baseline 3 the right call.

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 resource ('a run's') and enumerates the returned content (status, summary, pending approvals, final reply). This is far more than a tautology, but it never names or contrasts a sibling such as wait_for_run or list_runs, so sibling differentiation is absent.

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 implied: it is the read accessor for a single run, and the '(once settled)' clause hints at when the final reply is available. However, there is no explicit statement of when to prefer this over wait_for_run (which polls until settled) or list_runs, nor any prerequisite guidance.

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