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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint. The description adds API key requirement, cost for fetch_emails, states no lead is saved (side effect), and mentions return of firmographics. This adds meaningful behavioral context beyond annotations, though it doesn't describe exact response format or pagination. No contradiction.

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?

Description is front-loaded with core purpose, then usage guidance, then cost and side effects. Each sentence adds new information without fluff. Efficient and well-structured.

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 8 parameters and no output schema, the description covers key operational aspects: API key requirement, cost trigger, side effects, and return type. It doesn't mention pagination or error handling, but the limit parameter is already in schema. Adequate for the tool's complexity.

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 covers all 8 parameters (100% coverage), so baseline is 3. The description adds semantics by explaining filter combination (AND), clarifying that headcount and technology are firmographic criteria, and warning about fetch_emails cost. This goes beyond the schema to improve parameter understanding.

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 finds COMPANIES via firmographic criteria using Hunter.io, with optional email pulling. It explicitly distinguishes from search_leads by stating 'When they want named people, use search_leads,' giving a clear verb-resource and sibling differentiation.

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?

Provides explicit when-to-use guidance ('reach for it when the user is targeting organisations...') and when-not-to ('When they want named people, use search_leads'). Also explains filter combination logic (AND) and mentions cost implications for fetch_emails, giving practical usage context.

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