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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, so the safety profile is covered. The description adds genuinely new behavioral context beyond them: results are pre-validated for SMTP/deliverability on LeadMagic's side, and a confirmed miss costs 0 credits — useful for deciding whether to retry or escalate.

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 front-loaded sentences: purpose first, then the validation/cost trait, with a copy-pasteable invocation. The inline example largely duplicates the schema's `examples` block, which is the only mild waste.

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 should convey the return shape, and it only implies one ('every email returned', 'confirmed no-match'). It does not say what a miss looks like (null vs. error vs. status field) or anything about credit cost on a hit, which matters for an agent deciding to retry.

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 each parameter carries its own description and example, so the schema does the heavy lifting. The description only echoes the three required fields in prose and repeats the example already present in the schema, adding no format rules (e.g., domain normalization, name casing) beyond it. Baseline 3.

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 ('Find a work email') plus the exact lookup key set (first name, last name, company domain) and the backing provider (LeadMagic). No sibling tool in the list overlaps with email lookup, so disambiguation is moot, but the purpose is unambiguous and complete.

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?

Implicitly defines the required inputs and notes the cost outcome for a no-match ('0 credits'), which nudges toward using it freely. However, there is no explicit when-to-use/when-not guidance, no prerequisite caveats (e.g., what to do when the person's domain is unknown or a personal email is expected), and no named fallback.

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