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

With no annotations, the description carries the full burden. It thoroughly discloses behavior including caching (24h), error handling (400 on no match, not billed), and pricing ($0.001 per call). It also explains the return fields, leaving little ambiguity about the tool's operation.

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 dense but every sentence adds critical operational information: purpose, forward/reverse modes, parameters, return data, error handling, caching, and pricing. It is well-structured, starting with the core functionality and then layering details.

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?

The description covers many aspects: API source, input modes, parameters, output fields, error behavior, caching, and cost. However, it omits the fact that type and citycode are not actually supported by the MCP schema, and it does not mention potential rate limits. Still, given no output schema, the description is fairly complete.

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 description provides meaningful detail for q (with example) and limit (range and default), which the schema lacks. However, it also describes optional parameters 'type' and 'citycode' that are not present in the input schema, creating a misleading invocation path. This inconsistency harms the agent's ability to call the tool correctly.

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 clearly states the tool performs French address geocoding using the official Base Adresse Nationale. It distinguishes itself from sibling validation tools by focusing on geocoding, and it explicitly mentions both forward and reverse geocoding.

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 description provides clear context for when to use the tool (French address verification/geocoding) and explains the forward and reverse API usage. It does not explicitly mention alternatives or exclusions, but the purpose is distinct enough among siblings.

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