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

Goes beyond the readOnly/idempotent annotations by disclosing that results contain digests only and never payloads, that the call is free, that unknown ids are handled gracefully, and by naming the HTTP equivalent. Minor vagueness remains in 'the write-back events when built', which doesn't say when those are absent.

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?

One front-loaded sentence packs the verb, resource, output contents, and privacy caveat, followed by a short edge-case note and the HTTP mapping. No sentence is filler.

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 no output schema, the description compensates by enumerating the returned fields, and the single required parameter is documented. It leaves open how large the per-call record set can be or whether truncation/pagination applies, which is the only notable gap for a result-retrieval tool.

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?

Only one parameter and schema coverage is 100%, with the schema already stating the id comes from arena_run. The description reinforces the run_id semantics but adds no format, validation, or lookup behavior beyond what the schema provides, so baseline 3 applies.

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 ('read one run's status and result by run_id') and then enumerates exactly what comes back: lifecycle state, verdict, per-call records, write-back events. It is clearly the read counterpart to arena_run, so an agent can distinguish it from the sibling that creates the run.

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 'by run_id' framing plus the note that an unknown run id is answered free tells the agent this is a lookup on an existing run rather than a launcher. It doesn't explicitly say 'call arena_run first to obtain the id', though the schema parameter description does, so usage is clear but not fully spelled out in the description itself.

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