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

Annotations already declare read-only, idempotent, closed-world and non-destructive, so the bar is low, yet the description adds substantial context: the comparison is all-or-nothing ("Reject the whole comparison if any profile is unavailable"), unknown values and source evidence are preserved, prices are approximate ranges rather than quotes, locations are candidates only, and no winner/quality/compliance ranking is produced. These are real behavioral traits an agent cannot infer from annotations or schema.

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?

Five short sentences, front-loaded with the action and bounded scope, then constraint, then caveats. Every sentence adds a distinct rule or limitation; none restates the title or annotations.

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 two-parameter read-only comparison with an output schema already defined, the description covers the gaps that matter: failure semantics for missing profiles, treatment of unknowns, and explicit non-guarantees about price and quality. Nothing an agent needs to invoke it correctly is missing.

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%, so the description must carry the meaning. It does partially: "two or three distinct" maps to minItems/maxItems/uniqueItems and "one recorded service category" maps to the category enum. It never explains that slugs are lowercase-hyphenated provider identifiers or what 'published' means relative to a slug, so the compensation is incomplete.

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?

"Compare two or three distinct published providers in one recorded service category" gives a specific verb (compare), a bounded resource (2-3 published providers), and a scope (single category). It is clearly distinguishable from searching or fetching a single provider, though it never names the siblings search_providers/get_provider to make that contrast explicit.

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 arity (two or three) and single-category constraint imply when this tool is applicable, and the atomic-rejection rule is a usage-relevant constraint. However, there is no explicit statement of when to use this instead of search_providers or get_provider, nor prerequisites for obtaining valid slugs.

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