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

Annotations already declare readOnlyHint=true, so the read-only nature is covered. The description adds valuable context: 'No cost', 'cached' metrics (indicating not live), and the API key requirement. This goes beyond the annotations without contradicting them.

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 efficient sentence plus a parenthetical note. It front-loads the core purpose, then adds cost, use case, and auth requirement. Every word earns its place.

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?

The tool has only 2 params and no output schema, so the description carries the burden of explaining what the agent gets back. It lists the key metrics (clicks/impressions, domain rating, organic traffic, top keywords), gives cost and auth info, and states a specific use case. The only gap is the lack of a more explicit link to the days parameter in the return data, but overall it's reasonably complete.

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 coverage is 0% (no descriptions for siteId or days). The description mentions 'daily' trend and 'a site's performance', which loosely maps to the days and siteId parameters, but it doesn't explicitly explain their formats, ranges, or how days affects the trend. The description fails to compensate for the missing schema documentation.

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 starts with the verb 'Read' and specifies the resource: a site's performance metrics (Search Console clicks/impressions trend and cached SEO metrics). This clearly distinguishes it from sibling tools that generate content or calculate SEO scores.

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?

It provides an explicit use case: 'Use to check whether Spook is working' and notes the prerequisite of an agent API key. It doesn't discuss when not to use it or name alternatives, but the context is clear given the sibling set.

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