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

Annotations already declare readOnly/idempotent/non-destructive/open-world, so the bar is lower. The description adds genuine behavioural context beyond them: the check runs against daily open data (freshness), the name is verified but never returned (a privacy trait the agent must know before relaying results), and non-NYC cities fall back to guidance rather than a live result.

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-loaded with the tool's purpose and then the return semantics; no filler sentences. The second sentence is dense but each clause (active status, expiry, name match, name not returned) earns its place. Slight cost in readability for cramming the output contract into one sentence.

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?

With no output schema, the description does the work of explaining what comes back: active/expired status, expiry date, and a name-match verdict. That covers the main agent needs; it is only mildly thin on error/edge behaviour for unknown numbers or unsupported cities.

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%, so the schema already documents all three parameters including defaults and the meaning of 'number'. The description reinforces that 'name' is optional and is only used for a match test, but adds little beyond the schema, so the baseline 3 applies.

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?

Specific verb (check) plus a precisely scoped resource (New York taxi/ride-app driver's TLC licence) with the data source named (NYC's daily open data). It clearly distinguishes the NYC live check from the other-city guidance path, so an agent can tell it apart from fare/tariff siblings.

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?

Explains the two modes (live NYC check vs. official guidance for other cities) and the conditional behaviour when a name is supplied, which gives clear context for invocation. It stops short of naming an alternative sibling tool or stating explicit exclusions, but the when-to-use path is unambiguous.

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