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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description adds valuable operational context: free usage, no account/API key needed, returns estimated audience size, count of work emails, and 5 sample people with masked emails. It also notes the transition to the paid/full version via account connection, aligning with the openWorldHint.

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 a single, well-structured paragraph that leads with purpose, then return value, then usage guidance. Every sentence serves a distinct role: what it does, what it returns, cost/friction, and when to use it. 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?

For a tool with 8 optional parameters and no output schema, the description tells the agent exactly what to expect (estimated size, email count, 5 samples) and the circumstances for use. The parameter details are fully covered by the schema, so the description doesn't need to repeat them. It's complete for an agent to call 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?

Schema coverage is 100%—each parameter has a description with examples. The tool description lists the filtering dimensions but does not add new meaning beyond what the schema already provides. Baseline 3 is appropriate given the high schema coverage.

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 clearly states the tool's function: finding B2B leads for an ideal customer profile and returning the estimated audience size. It lists specific filtering dimensions (job titles, seniority, department, industry, company size, location) and distinguishes itself from search_b2b_leads by clarifying it returns only preview data, not full verified emails.

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?

Explicitly instructs when to use this tool ('Use it first to size a market or check a targeting idea') and provides a direct alternative for full emails ('to get full verified emails... call search_b2b_leads'). This leaves no ambiguity about when to choose this tool over its sibling.

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