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

Annotations already establish a safe read-only, non-open-world operation. The description adds useful behavioral context: it reports tool/day usage plus monthly quota and requires an organization API key. It does not cover pagination or return format, so not a 5.

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?

Two sentences, front-loaded with the returned metrics and followed by the access prerequisite. No redundant or filler language.

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 simple one-parameter read tool with annotations and no output schema, the description supplies the metric list, scope, quota inclusion, and auth requirement. Nothing material is missing for correct selection or 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 coverage is 100%, so the gw_id parameter is already documented as a 'gw_... ID'. The description reinforces that the parameter selects 'one of your gateways,' but adds no format or selection detail beyond the schema.

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?

States exactly what is returned—calls, errors, denials, x402 payment prompts, per tool and per day, plus monthly quota—for a specified gateway. The metric/scope phrase clearly distinguishes it from gateway_info, gateway_list, and guard_balance.

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 gateway scope and 'Requires the organization API key' establish when it is usable, but there is no explicit alternative routing such as 'use gateway_info for metadata.' Usage is implied rather than fully guided.

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