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

Annotations only declare readOnly=false, destructive=false, openWorld=false; the description goes well beyond that by disclosing billing semantics (suppressed/ineligible and previously owned contacts consume zero records) and the limits of the screening (checks do not prove a mailbox exists). These are exactly the behavioral traits an agent needs before spending customer credits, and they are consistent with readOnlyHint=false.

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?

Purpose and source are front-loaded, then prerequisites and billing caveats follow in logical order. Every sentence carries information, though the suppression/DNS passage is dense enough that it could be tightened slightly.

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 mutation-style, credit-consuming tool with only minimal annotations and no output schema, the description covers preconditions, customer-consent requirements, and billing edge cases well. It never states what the agent receives back on success (e.g., the unlocked contact fields), which is a minor remaining gap given no output schema exists.

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 lead_id parameter is already described in the schema as 'Lead ID returned by search_people.' The description repeats that provenance but adds no new syntax, format, or constraint detail, 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?

States a specific verb+resource ('Unlock one B2B contact') and pins the input to a known source ('identified by search_people using its lead_id'). This distinguishes it from the sibling search_* tools, which retrieve lists rather than unlock a specific record.

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 gating condition ('Use this tool only when the customer requests access to a specific contact') and a pre-invocation obligation to inform the customer. It also names search_people as the prerequisite source of lead_id, so the agent knows the required call sequence.

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