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

Annotations already declare readOnlyHint=true, covering the safety profile. The description adds pricing and plan context but little additional behavioral detail such as resolution uniqueness, failure modes, or what happens when no provider is found. The schema's context parameter description does add some transparency, but the tool description itself is thin.

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 compact and front-loaded: purpose, usage rule, then pricing. The pricing/plan sentence is somewhat operational rather than selection-focused, but it is not filler and the whole description remains short and readable.

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 resolver with one required, fully documented parameter, the description plus schema gives enough to understand what to pass and what to expect ('the provider it belongs to'). It does not describe output shape or error behavior, but the absence of an output schema makes that a minor gap rather than a blocking one.

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%, and the description's identifier examples (URL, domain, GitHub org) duplicate what the schema already says. The optional context parameter is well documented in the schema, so the description adds no new parameter-level meaning beyond the structured fields.

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 opens with a specific verb and resource: 'Resolve ANY identifier ... to the apis.io provider it belongs to.' It enumerates the accepted input forms (URL, domain, GitHub org) and explicitly contrasts with slug-based lookups, making it easy to distinguish from sibling tools like get_provider or find_providers.

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?

It gives a clear decision rule: 'Use this when you have a URL, not a slug.' This tells the agent when to invoke this tool and implicitly when not to, though it does not name the alternative for slug inputs or discuss other exclusions.

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