Compare Runs

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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safe-read profile is covered. The description adds some value by noting that evaluations must be 'compatible' and that the metric policy is optional, but it does not explain what compatibility means, what happens if runs are incompatible, or how the optional policy affects behavior.

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?

The description is a single, front-loaded sentence with no padding. It is appropriately sized, though the phrase 'compatible evaluations using an optional explicit metric policy' is somewhat jargon-heavy and could be clearer without adding length.

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 comparison tool with four parameters at 0% schema description coverage, the description is too thin. The output schema means return values need not be explained, and annotations cover safety, but the description still fails to explain compatibility, the role of the baseline and candidate run IDs, or how the metric policy is applied.

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 0%, so the description must compensate for all four parameters. It only vaguely gestures at an 'optional explicit metric policy,' which might loosely relate to the metric and direction parameters, but it says nothing about baseline_run_id or candidate_run_id and does not clarify the direction enum or metric format.

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 ('Compare') and an object ('compatible evaluations'), which gives a basic sense of the tool's purpose. However, 'compatible evaluations' is vague and the description never mentions the baseline/candidate run IDs that are central to the operation, so it does not distinguish this tool clearly from siblings like evaluate or evaluation_get.

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?

There is no guidance on when to use this tool versus alternatives such as evaluate, evaluation_get, or evaluation_failures. The phrase 'optional explicit metric policy' hints at a default behavior but does not explain when to supply a policy or when an implicit policy is sufficient.

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