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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds that results are 'current' facts scoped to a single subject, which is useful, but says nothing about invalid-subject handling or return format.

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, verb-first, with no filler. The subject enumeration is dense but justified given the 0% schema coverage; the only mild awkwardness is 'facts on one subject'.

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 read tool with no output schema and full annotation coverage, the description supplies the key missing piece (valid subject values). Only error/edge behavior for unrecognized subjects is absent.

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 0% for the single required parameter, so the description carries the burden — and it does so by enumerating the accepted subject values (deposit, balance, cancellation, etc.). It does not specify matching rules such as case sensitivity or exact-string requirements, so it falls short of full compensation.

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?

Specific verb (returns) and resource (booking policy facts) with a scope qualifier ('on one subject'). The enumerated subject list makes it distinguishable from siblings like search_facts, though it never names those siblings explicitly.

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 subject enumeration implies the required usage pattern, but there is no statement of when to prefer this over how_to_book, list_topics, or search_facts, and no exclusions. Usage is inferable rather than stated.

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