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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and openWorld, so the safety profile is covered. The description's only added behavioral fact is "Keyless" (no API key required), which is genuinely useful but thin; return format and pagination are not described. A 3 fits given the annotations carry most of the burden.

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?

Front-loads the core action, folds in illustrative examples efficiently, then closes with the routing hint. Every clause earns its place, including the terse "Keyless." fragment.

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-optional-param, no-output-schema lookup tool, the description explains what is returned (title numbers plus official names) and how it fits the workflow. Adequate; only the exact response shape (e.g., ordering, count confirmation) is left implicit, which is minor.

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 coverage is 100% and the single optional 'subject' param already includes examples in the schema. The description reinforces its purpose (filter by known subject) but adds no syntax or format detail beyond the schema. Baseline 3.

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 a specific verb (List) and resource (the 44 titles of the Colorado Revised Statutes with official names), and even samples the content (Title 18 Criminal Code, 42 Vehicles, 38 Property). An agent can distinguish it from co_statute and co_search immediately.

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 states the triggering condition ("Use when you know the subject but not the title number") and routes the agent to the follow-up tools ("before calling co_statute or co_search"). Both when-to-use and the alternative are named.

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