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

Annotations already declare destructiveHint=true and readOnlyHint=false; the description adds the reasons behind that profile — credit use, a required confirmed=true approval gate, and no automatic retry of writes. This is useful context beyond the annotations, though it doesn't explain result limits or rate behavior.

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?

Four short sentences front-load the purpose before the approval/credit/retry caveats. The opening 'Check DNC status.' slightly duplicates the following sentence, but there is minimal waste overall.

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 helpfully states the return values (DNC status and phone type). It also covers the approval and retry behavior. Only minor gaps remain around batch/pagination and what 'phone type' values mean.

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 50% and the schema already describes both the phones array (max 1,000) and the confirmed flag. The description repeats 'array of phone numbers' and 'confirmed=true' without adding format or validation detail beyond the schema. Baseline 3 is appropriate.

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 (check) and resource (DNC registry status and phone type) for an array of numbers. It explicitly distinguishes itself from a full person enrichment, which routes the agent away from siblings like dealmachine_enrich_phone.

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 'without performing a full person enrichment' clause implies when to prefer this over an enrichment tool, and it notes approval is needed for credit use. However, no sibling is named explicitly and there are no stated when-not conditions, so usage is only implied.

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