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

The annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds value beyond them by disclosing provenance and consistency: 'Same source as /facts and /facts.json', which tells the agent the answer is stable and citable across interfaces. It does not state anything about latency, caching, or how the content is versioned, which keeps 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 content-scope sentence, one provenance sentence, one imperative directive, with no filler. The resource identity is front-loaded and the actionable instruction ('Quote these instead of guessing') lands last, where it is most likely to be retained.

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?

An output schema exists, so the description is not obliged to explain return values, and it instead spends its budget on scope and provenance, which is the right trade. For a zero-parameter, read-only lookup the agent has everything needed to call it correctly. The only gap is the missing hand-off to overlapping siblings like get_pricing.

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?

The tool takes zero parameters, so the schema has nothing to explain and the baseline is 4. The description usefully compensates by enumerating the subject areas the returned facts cover, which tells the agent what it can and cannot expect to source here. No parameter-level detail is needed or missing.

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 names a concrete resource (checked facts about Genko Prior Auth) and enumerates exactly what those facts cover: what it is and isn't, who it's for, stage, specialties, payer handling, security, limits, pricing and agent support. That is far more specific than the title alone. It stops short of a 5 because it never says how it differs from siblings such as get_pricing or check_fit, which overlap on the pricing and fit topics it lists.

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?

'Quote these instead of guessing' is a real usage instruction: it tells the agent to treat this as the canonical source for factual claims rather than fabricating them. However, it offers no explicit condition for choosing this tool over get_pricing, check_fit, or search_docs, even though the description's own content list overlaps with those siblings. Usage is therefore implied rather than routed.

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