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

Annotations already cover read-only, idempotent, and non-destructive semantics, so the bar is lower; the description adds genuinely new context by stating the plan requirement (Creator Max or agency Pro/Scale/Enterprise) and that the email is conditional on prior reveal. It stops short of describing pagination or auth mechanics, but the plan gating is meaningful operational intelligence.

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?

Two sentences: the payload contents lead, followed by the eligibility constraint. No filler, and the most decision-relevant information (returned fields) is front-loaded; the plan sentence is dense but earns its place.

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?

An output schema exists, so return values need not be restated; the description covers the two things the agent most needs beyond the schema: the entitlement gate and the conditional email state. Minor gaps around rate limits or the reveal hand-off remain, but the definition is complete enough to invoke correctly.

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?

With a single parameter at 100% schema description coverage, the schema fully documents person_id (pattern plus its origin). The description adds no param-level detail beyond what the schema provides, so the baseline of 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 and resource ('Return one influencer-marketing contact') and enumerates the returned fields, which distinguishes it from sponsor_search_contacts by scope ('one'). It does not explicitly name the sibling it complements, but the resource is unambiguous.

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?

Usage is implied rather than stated: the schema note that person_id comes from sponsor_search_contacts and the phrase 'when already revealed' hint at a search-then-get-then-reveal workflow. There is no explicit when-to-use/when-not or direct pointer to sponsor_reveal_email.

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