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

Annotations already establish readOnly, idempotent, non-destructive behavior, so the description does not need to restate those. It adds context about optional data fields and shows an API key in the example, but otherwise does not disclose behavioral details like response shape, potential errors, or rate limits. This is adequate given the annotation coverage but not exceptional.

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 concise: a clear first sentence, a brief mention of optional fields, and a concrete example. Each part earns its place, though the example partially duplicates the schema examples. It is front-loaded and easy to scan.

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 reverse-geocoding tool, the description covers the core operation, optional fields, and an example. It lacks an explicit statement of the return format, but 'to the nearest street address' sufficiently implies the output. The annotations and schema fill in remaining safety and parameter details, making this complete enough for correct invocation.

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 input schema already provides 100% parameter coverage with detailed descriptions for q, limit, fields, and _apiKey. The description's example is helpful but largely restates what the schema already includes, so it adds little semantic value beyond the structured definitions.

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 states a specific verb and resource: 'Reverse geocode a coordinate pair to the nearest street address.' This clearly distinguishes it from sibling tools like geocodio_geocode (forward geocoding) and geocodio_batch (batch operations). The optional data-field mention adds scope without ambiguity.

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?

Usage is implied by the phrase 'Reverse geocode a coordinate pair' and the example, but the description does not explicitly guide the agent on when to choose this tool over geocodio_geocode or geocodio_batch. No exclusions or alternative recommendations are provided, so the guidance is functional but not fully elaborated.

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