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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world behavior. The description adds no behavioral context beyond annotations—no auth requirements, rate limits, or note on whether the run must be complete. It only describes the informational components of the explanation.

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?

Single front-loaded sentence with no filler; every word contributes to the purpose. Appropriately sized for a simple read-only tool.

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 one-parameter read-only tool with a full output schema and comprehensive annotations, the description gives enough to call it correctly. It does not distinguish from sibling baseline.lineage or mention runs.list as the runId source, but those gaps are minor and partly covered by the schema.

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%; runId is fully documented in the schema, including format and source (runs.list). The description adds no parameter-level detail, so the baseline of 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 the specific verb 'Explain' and resource 'run', and identifies the informational components used: status, failed-case metadata, and evidence-lineage summary. It does not explicitly name sibling alternatives like runs.list or baseline.lineage, so it is clear but not differentiated from siblings.

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?

Provides no explicit when-to-use, when-not-to-use, or alternative guidance. The only implied context is that it is for understanding a run, which essentially restates the purpose. Alternatives such as runs.list are not mentioned.

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