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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds two genuinely new behavioral facts — that the call is free and moves no money — but says nothing about whether the policy is a live snapshot, how often it changes, or whether it varies per account/workspace.

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?

A single dense sentence with the resource and its fields front-loaded, plus a short safety/cost tag. No filler, nothing repeated from the annotations or schema.

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 no output schema, the description must stand in for return values, and it does so by naming the concrete fields an agent will receive. It stops short of noting scope (per-account vs global) or freshness, which would matter for a policy-read tool.

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 tool takes zero parameters, so the baseline is 4. The description correctly implies a no-argument call that returns the ambient policy, and there is nothing further a parameter discussion could add.

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 names a specific resource and enumerates its contents: live rail/network, per-transaction and daily caps, settled-per-hour limit, allowlist state, and the 50 bps fee. An agent can tell it is a read of the current routing configuration, but nothing distinguishes it from gatepay_status or gatepay_route, which are never mentioned.

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?

There is no statement of when to call this versus gatepay_quote, gatepay_route, or gatepay_status. 'Free; moves no money' tells the agent about cost, not about the selection condition, so an agent must infer that it should check policy before routing.

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