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

Goes well beyond the readOnlyHint/openWorldHint annotations: states the 20-facility cap per call, typical and worst-case latency with a recommended 30 s timeout, x402 pricing at $0.002 USDC per successful call with payment chains (Base, Solana, Arc), and that failed calls are not charged. Cost and latency disclosure is exactly what an agent needs before invoking a paid, network-bound tool.

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 purpose and returned fields, then input constraint, then limits/cost. Every sentence carries payload, though the pricing clause is dense and could be split for readability.

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?

Covers input constraint, result cap, latency, timeout, and payment mechanics; an output schema exists so return-value explanation is not required. It omits whether results beyond 20 are reachable via pagination or only radius expansion, a minor gap for a 4-parameter tool.

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 description coverage is 100%, so the baseline is 3. The description reinforces that lat/lng are required and that 20 is the ceiling on results, but adds no format, rounding, or radius semantics beyond what the schema already documents.

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+resource: 'SAMHSA FindTreatment substance use and mental health treatment facilities near a latitude and longitude', and enumerates the returned fields (name, address, phone, website, miles, facility type). An agent can immediately tell this is a proximity search over treatment facilities, distinct from the registry/lookup siblings listed.

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 constrains invocation to coordinate input ('Give lat and lng; ZIP or city search is not offered'), which prevents a common wrong usage. It does not name an alternative tool or exclusionary conditions, but no sibling is close enough to require routing guidance.

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