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

Annotations already disclose non-read-only, non-destructive, idempotent behavior, so the burden is partly lifted. The description adds the useful auth requirement ('Requires API key'), but says nothing about what creation changes or what a list returns. Note the idempotentHint=true sits oddly with a create action, though the description does not contradict it directly.

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 short, front-loaded sentences with no filler. The only blemish is the inaccurate 'baseline' mention, which costs a sentence its full value.

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 six-parameter, dual-action tool with an output schema and full schema coverage, the description covers the essentials: the two modes and the auth requirement. Return details are handled by the output schema, so the remaining gap is minor.

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%, so the baseline is 3. The description echoes 'hypothesis' (a real parameter) but also mentions 'baseline', which is not a parameter at all, adding a small amount of noise rather than meaning.

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 concrete verb pair (create/list) and the resource (SEO experiments), so the agent knows the tool's job. It does not differentiate itself from any sibling, and the name 'run_experiment' is looser than the actual create/list behavior described. The reference to 'baseline' also doesn't map to any real parameter.

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 description implies the two modes via 'create or list', which mirrors the 'action' enum, so usage is inferable. There is no guidance on when to choose this over sibling tools like monitor_site or seo_audit, and no exclusions or prerequisites beyond the API key note.

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