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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so the safety profile is covered. The description adds genuinely useful context beyond that: it is free, requires no wallet or payment, takes no arguments, and returns a sample rather than real geocoding output.

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?

A single tight sentence, front-loaded with [FREE], that conveys pricing, prerequisites, and purpose with no waste.

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 zero-param preview with no output schema and rich annotations, the description is essentially sufficient, though it promises 'see the shape' without hinting at what fields the sample contains (forward/reverse geocode result), a small gap given the absent output schema.

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?

With zero parameters the baseline is 4, and the description confirms 'no arguments needed', matching the empty schema with additionalProperties:false. Nothing further is required 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?

States precisely what the tool returns (a sample response for address_geocode) and its role (preview before paying), which cleanly distinguishes it from the sibling address_geocode and from the other *_preview tools. An agent can immediately tell this is a static demo rather than a live geocoder.

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?

Explicitly frames the when: 'so you can see the shape before paying 0.008 USDC', and the 'no wallet, no payment' clause removes preconditions. It stops short of naming address_geocode as the alternative for real lookups, leaving that routing to inference from the name.

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