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

Annotations already declare readOnly, idempotent, non-destructive, openWorld, so the safety profile is covered. The description adds useful content-level behavior: it is a static llms.txt-style index and precisely what fields each entry carries. It does not discuss size/pagination, but for a fixed index that is minor.

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 sentences, front-loaded with the resource and payload, followed by usage and the sibling hand-off. No filler or restatement of the title.

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 takes on the return-value burden and discharges it by naming the exact fields (title, one-line description, Markdown URL). For a no-parameter read-only index tool, an agent has everything needed to call it and use the result.

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?

Zero parameters, so the 4 baseline applies. The description explicitly confirms 'No parameters', matching the empty schema with additionalProperties false, removing any doubt about how to invoke it.

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 resource (the docs' llms.txt index) and exactly what it contains: every documentation page's title, one-line description, and Markdown URL. It is clearly distinguishable from siblings spicrawl_docs_search and spicrawl_docs_read, both of which are named in the text.

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 explicit when-to-use conditions: 'find the right page when a search does not' and 'get an overview of what is documented', and routes to the correct alternative for the follow-up step ('read a page with spicrawl_docs_read'). Nothing is left to inference.

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