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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds valuable context: that the tool always works without workspace targeting, and explains the 'truncated' flag behavior (page cut at section boundary, full page available via returned url). This goes beyond 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?

The description is concise, with three sentences that are all information-dense. It front-loads the core action and then adds usage guidance and a behavioral note. No redundant or filler language.

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 simple single-parameter tool with an output schema available, the description covers all necessary aspects: how to obtain the URL, the behavior of truncated responses, and the always-available nature. The output schema likely explains the returned structure, so no further detail is needed.

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 schema already explains the url parameter well. However, the description reinforces the valid sources for the URL and adds the constraint that only docs.extend.ai URLs are fetchable, which is not fully explicit in the schema. This adds meaning beyond the schema.

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 clearly states the verb ('Fetch') and resource ('Extend docs page') and specifies the output format (markdown) and source (docs.extend.ai). It distinguishes itself from siblings like search_documentation by indicating it fetches a specific page rather than searching.

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 explicitly tells when to use this tool: pass a URL from a tool description, an error's docUrl, or a search_documentation result. This provides clear context and implicitly differentiates from search_documentation, which is for searching rather than fetching a known URL.

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