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

Annotations already cover readOnly and idempotent, but the description adds important behavioral details: it ranks candidates, provides a match score and match_quality flag with specific meanings ('exact' certain, 'likely' shares house number, 'weak' no house number match). It also discloses that the service is free and unlimited, which is not in annotations. This gives agents a complete picture of what to expect.

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 front-loaded with the key selling point (free, no signup) and then methodically explains the input, output, and usage. Every sentence carries useful information—coverage, match quality, and the follow-up tools. It is a bit long but not redundant.

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 single-parameter search tool with no output schema, the description is remarkably complete. It explains the output fields (address, city, ZIP, match score, match_quality), the semantics of match_quality, and the expected follow-up actions. An agent would know exactly how to call it and interpret the results.

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 schema already fully describes the 'address' parameter with a min length and example. The description adds a concrete example with trailing city/state/ZIP and clarifies that full or partial addresses are acceptable. While this is helpful, it's a minor addition given the schema already covers the meaning.

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 verb 'Resolve' and the resource 'Cook County / Chicago street address to its parcel PIN(s)'. It also distinguishes this from siblings by explicitly saying to call it FIRST when you have an address but not a PIN, and then pass the pin to sibling tools like get_cook_county_parcel. This leaves no ambiguity about the tool's role.

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 explicitly states when to use this tool: 'Call this FIRST when you have an address but not a PIN'. It also explains the match_quality flag and warns not to rely on weak hits, providing clear usage boundaries. It doesn't state when not to use it, but the positive guidance is strong enough.

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