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

Annotations already mark the operation as read-only, open-world, and idempotent. The description adds valuable behavioral context beyond these: it clarifies the semantic of 'transit' (AS path passes through), the truncation limit, and the query cost. No contradictions with annotations.

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 compact and front-loaded with the core purpose. Every sentence earns its place: purpose, differentiation, and constraints. 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 single-parameter tool with an output schema, the description covers all essential aspects: what it returns, how it differs from a sibling, operational limits, and cost. Nothing critical is missing.

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 the schema already fully describes the asn parameter (integer, range, examples, format). The description does not add further parameter-specific guidance, but the baseline of 3 is appropriate given the high 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 states a precise verb-resource pair: it lists prefixes whose AS path passes through the given AS, i.e., the customer cone. It also immediately distinguishes itself from the sibling pwhois_asn_prefixes by clarifying 'Transited, not originated', making its purpose unambiguous.

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 provides a usage alternative: for originated prefixes it directs to pwhois_asn_prefixes. It also notes practical constraints (2,000-row truncation, cost of 1 query), giving the agent clear conditions on when this tool is appropriate and what to expect.

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