fleet_usage

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

Annotations declare readOnlyHint=true, so the description does not need to restate safety. The description adds value by disclosing the exact metrics returned (tokens, cost, quota, saved tokens, breakdown), which is behavioral information beyond the annotation. It does not describe pagination or output structure, but for a read-only report this is adequate.

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 a single dense sentence that front-loads the purpose ('How much the fleet was used and what it saved') and then enumerates the metrics. It is efficient with no redundant phrases, and the parameter guidance is appended cleanly. Every clause 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?

With no output schema, the description must convey what the tool returns. It lists many metrics (tokens per node/model, cost, quota, saved tokens, category breakdown) and explains the default scope and days parameter. It does not mention sorting, pagination, or the exact format of the breakdown, but for a report tool this is reasonably complete.

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 50%: `days` has a description, but `scope` does not. The description explicitly clarifies scope ('scope ''all'' for every project') and confirms days is a period ('`days` for a period'), adding meaning beyond the schema. It effectively compensates for the undocumented scope parameter.

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 tool's purpose: reporting fleet usage and savings, with a specific list of metrics (tokens per node/model, cost, quota, saved tokens, category breakdown). It is distinct from sibling tools like fleet_status (likely health/state) and fleet_nodes (node management) by focusing on usage metrics, so an agent can select it correctly.

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?

Provides concrete usage context: 'This project by default; scope ''all'' for every project, `days` for a period.' This explains how to use the scope and days parameters, which is helpful. It does not explicitly mention when not to use this tool versus alternatives like fleet_status, but the purpose is clear enough that an agent can infer when a usage report is needed.

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