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

Beyond the readOnlyHint annotation, the description discloses that saved contact searches are free and instant, the profile page hides emails, revealing emails costs credits, and load_more_contacts handles pagination. This provides rich behavioral context for side effects and costs.

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?

The description is four sentences long, each adding distinct value: operation, behavior, examples, and alternatives. It is front-loaded with the most important information and contains no filler.

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?

Despite lacking an output schema, the description thoroughly explains the two-phase search, hidden emails, credit cost for reveal, and pagination, giving the agent a complete picture of expected results and follow-up actions.

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?

The query parameter is well illustrated with natural language examples, and the description implies the limit's role via 'up to 50 profiles' and pagination guidance. However, the limit parameter's ability to go up to 200 is not explicitly described, leaving a small ambiguity.

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?

The description opens with a clear statement: 'Search for contacts by title, company, or query.' It provides concrete example queries and distinguishes itself from sibling tools by explicitly mentioning find_email for email reveals and load_more_contacts for pagination.

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 guidance is explicit: it notes that saved Xmagnet contacts are searched first, then a free profile page; it instructs to call find_email for email reveal and load_more_contacts for subsequent pages. This clearly delineates when to use this tool versus alternatives.

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