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

Annotations already declare readOnly, idempotent, openWorld=false and non-destructive, so the safety profile is covered. The description adds behavior the annotations do not: the response is human-readable text plus a page URL, which matters because there is no output schema. It omits error behavior for a missing id, keeping it below a 5.

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?

One sentence, front-loaded with the verb and the identifier constraint, with the return format appended. Nothing is redundant with the annotations or schema.

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 single-parameter read tool with full annotation coverage, the description supplies the one thing structured fields cannot: what comes back (text + URL), which substitutes for the absent output schema. Only edge-case behavior (unknown id, not-found) is unaddressed.

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% and the single id parameter is already documented, so the baseline is 3. The description adds provenance semantics — the id must come from search results — which is meaningfully more than the schema's bare type/description.

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 ('Fetch') and resource ('one facility by id') plus the return shape ('readable text plus its page url'), which separates it from search/search_facilities/list_wards siblings. The parenthetical ties the id back to the search tool, making the retrieval-by-id contract unambiguous.

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 phrase 'id (as returned by search)' clearly implies this tool is used as a follow-up to search rather than as a discovery tool, which is the key routing decision. It stops short of explicitly excluding alternatives or stating what to do with an unknown/expired id, so it is clear context rather than full when/when-not guidance.

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