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

Adds substantial behavior beyond the annotations: it is labeled a MUTATION, is FREE (no credits), and crucially discloses partial-failure semantics ('one bad or duplicate row never aborts the rest') plus the per-row added/duplicates/errors reporting. This directly explains the non-idempotent duplicate handling the annotation only flags as a hint.

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?

Single dense sentence-pair that front-loads the bulk/scope facts and then the mutation and error semantics. The 'Link Building Tool:' prefix is mild filler, but otherwise every clause 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?

For a mutation tool with no output schema, the description covers cost, partial-failure behavior, and the shape of the response summary. It omits permission/auth requirements and does not explicitly route against add_link_prospect, but the essentials an agent needs to call it safely are present.

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 100%, so both parameters are already documented, including projectId's origin from list_projects. The description's 'each with at least a domain' and the 500 cap restate what the schema already enforces (minItems/maxItems, required domain), so 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 and resource ('bulk-add ... prospects'), plus concrete scope (up to 500, from already-parsed rows with at least a domain). It implies but never names the single-item sibling add_link_prospect, so sibling differentiation is left to inference. Clear enough to know what the tool does without opening the schema.

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?

Conveys implied usage through 'bulk-add up to 500 prospects at once' and contrasts with a single-add flow only implicitly. There is no explicit when-to-use vs add_link_prospect or when-not guidance, and no prerequisites beyond the schema. The FREE note is context, not routing.

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