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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, openWorldHint=false), so the bar is lower. The description still adds real behavior: the accepted slug input forms and the fact that include_examples returns code already present in the body, which prevents redundant fetches. No contradiction with annotations.

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?

Three sentences, front-loaded with the return payload, then input flexibility, then slug sourcing, then the sibling comparison. Every sentence carries information; slight density but no 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 flagging that the body contains the page's HTML/CSS code. Combined with annotations and full schema coverage, an agent has everything needed to call it correctly.

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 100%, so baseline is 3, but the description genuinely extends the schema: it documents a third accepted slug format (a page link like '/email-playbook/compatibility/responsive/') that the schema description omits, and clarifies that include_examples is additive rather than a filter.

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 ('Return one rule page') and enumerates exactly what comes back: slug, category, title, description, checklist, and markdown body. It also distinguishes itself from get_playbook_rules by noting it is 'much smaller than fetching the whole category', so an agent can separate the two without opening schemas.

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?

Gives a clear entry point ('Get the slugs from list_categories') and names the alternative (get_playbook_rules) with the condition that favors this tool (single rule vs. whole category). It stops short of explicit when-not-to-use guidance, but the routing context is unambiguous.

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