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

Annotations only declare readOnlyHint=false, destructiveHint=false, openWorldHint=false; the description goes far beyond that by disclosing billing semantics (one fixed billable hit when newly acquired; my_data and unavailable are total_cost=0), the return-status enum values, the absence of a count_only quote, and subscriber compliance responsibility.

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 core action and required parameter, and nearly every sentence carries operational value (billing, statuses, chain). The nationwide coverage line is the one near-filler sentence, and the text is dense enough that it approaches a wall of facts rather than scannable structure.

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 2-param billable tool with no output schema and no annotation coverage of billing, the description supplies everything an agent needs: input format, default field set, billing outcome per status, and the upstream chain. No meaningful gap remains.

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 0%, so the description carries the full burden and does: person_id is documented as the REST PersonKey string with an example, and fields is documented with its default (Standard), the fact that Standard and All return the same four Product email ids, and that comma-separated ids from get_fields are accepted.

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 and resource (acquire/re-fetch billable email contact data for one Person) plus the exact key format (person_id, e.g. p4290). It explicitly contrasts itself with get_person_phones and get_person_relatives, so the agent can distinguish it from siblings without opening schemas.

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?

Gives an explicit trigger condition ('when the user wants emails only') and names the two alternative tools for other contact data. It also supplies the typical call chain get_property_persons → PersonID → get_person_emails, leaving nothing to inference.

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