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

Annotations already cover readOnly, idempotent, and non-destructive behavior. The description adds genuinely useful context beyond those: this is a paid resource with a specific x402 price, and it scopes the ranking to caller-supplied signals. It does not contradict the 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?

Three short sentences that front-load the core function, then add exclusions and cost. No fluff or repetition; every sentence earns its place.

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 nested-object tool with no output schema, the description covers purpose, exclusions, and cost adequately. It does not name sibling selection_routing_router_f8d62d68, which is a notable gap given the near-identical tool name, but the description is sufficient for basic correct invocation.

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 description coverage is 0%, so the description must compensate. It does clarify the roles of 'weights', 'constraints', and 'candidates' by naming the signals used. However, it omits details such as required candidate fields, units for latency/price, boolean flags like permission_ok/payment_supported, and weight/constraint defaults.

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 specific verb ('Ranks') and a clear resource ('caller-supplied candidates') using explicit signals, weights, and constraints. It is unambiguous, but it does not differentiate from the sibling 'selection_routing_router_f8d62d68' or other routing tools, so it stops short of a 5.

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?

It explicitly states the intended use ('selection routing / settlement failure') and gives clear when-not-to-use guidance ('Do not use for legal, identity, sanctions, fraud, contractual, or regulatory adjudication'). However, it names no alternative tools or the conditions that would make a sibling more appropriate.

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