route_gateway

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

Since no annotations are provided, the description carries the full burden. It discloses a rate limit ('100 free routes/month'), a non-requirement ('no API key'), and the nature of the response (payTo URL + totalCost), implying a read-only lookup. It does not explicitly state side effects (e.g., mutating state), but the context of routing suggests no permanent changes. It provides meaningful behavioral context beyond the schema, though it could be more explicit about idempotency or external calls.

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. The first sentence establishes the tool's unique value ('one call, best verified x402 endpoint'), followed by what it routes, its output, its usage context, and then a key constraint. Every sentence earns its place with no fluff, making it efficient and easy to scan.

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?

Given the tool has six parameters (all schema-described) and no output schema, the description covers the essential execution details: how to use it, what to expect in return, and usage limits. It does not elaborate on routing strategy nuances or error cases, but the schema fills those gaps. For a routing tool, the description is sufficiently complete for an agent to invoke it correctly without additional investigation.

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 schema has 100% coverage, so all six parameters are documented with descriptions. The tool description adds only a high-level hint that routing considers 'trust score, price, latency, and canary,' but this does not substantially supersede the schema's per-parameter details (e.g., defaults, enums). Given the baseline of 3 for full schema coverage, the description does not add enough extra semantic value to raise the score.

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 action ('Routes by trust score, price, latency, and canary') and the resource ('Cleared Gateway') and specifies the output ('Returns payTo URL + totalCost'). It distinguishes the tool from siblings by positioning it as the routing step after lookup_merchant, making its role 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?

The description gives explicit usage context: 'Use after lookup_merchant when you need category routing.' This tells the agent when to invoke it relative to a sibling. However, it does not explicitly state when NOT to use it or mention alternatives (e.g., list_cleared_services) for filtering or discovery, so it lacks exclusions. The guidance is clear but not exhaustive.

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