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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond annotations: it discloses that the tool resolves mobile share links and canonicalizes URLs automatically, and that it returns public information only. It doesn't mention rate limits or pagination, but for a read-only fetch tool the key behaviors are disclosed.

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 two sentences: the first states the core function and return data, the second gives the parameter selection rule. Every sentence earns its place, and the most important operational guidance (prefer url) is front-loaded in the second sentence. No filler or redundancy.

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 read-only tool with 3 optional parameters, 100% schema coverage, and no output schema, the description covers the essential context: what it fetches, what it returns, and how to choose parameters. The only minor gap is that it doesn't explicitly state what happens if multiple parameters are provided or if none are provided, though 'exactly one' implies the constraint. Overall it's complete enough for an agent to invoke 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 description coverage is 100%, so the schema already documents all three parameters thoroughly. The description adds value by prioritizing url over the others and explaining the resolution behavior, which complements the schema's per-parameter descriptions. It doesn't add much beyond the schema, but the baseline of 3 is exceeded by the explicit preference rule and the 'exactly one' constraint.

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 states a specific verb ('Fetch') and resource ('public business page information from Facebook'), and enumerates the exact data returned (name, category, address, phone, website, ratings, reviews, followers, photos). It clearly distinguishes itself from sibling tools like instagram_profile and tiktok_profile by focusing on Facebook business pages.

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 gives explicit selection guidance: 'Provide exactly one of page_id, username, or url — prefer url when the user pasted any Facebook link (including mobile share links), since the tool resolves the canonical page automatically.' This tells the agent when to use each parameter and why url is preferred, which is actionable routing guidance.

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