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

With annotations already declaring readOnlyHint and idempotentHint, the description adds meaningful behavioral context: the daily quota is a shared organization aggregate rather than project or historical usage, unavailable data is not zero, and reading quota does not reserve capacity or authorize deployment. These are valuable caveats beyond the structured annotations, though authentication, rate limits, and response shape are still not covered.

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 front-loaded with the core operation, followed by practical caveats about the month, quota aggregation, and unavailable data. The sentences are mostly efficient, though the reference to 'the same evidence as Eurobase Usage' is somewhat vague and the caveats could be tightened slightly.

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 two-parameter read-only usage tool with rich annotations and no output schema, the description provides enough behavioral context to call it correctly, especially around quota semantics and missing data. It stops short of describing the return shape or exact cost/usage fields, which would help compensate for the absence of an output schema.

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 for both parameters. It explains that 'month' is YYYY-MM with the current month as default, which adds useful meaning beyond the schema pattern. For 'projectId' it only implies that the selected project is identified, leaving the required project identifier largely undocumented beyond the schema's format pattern.

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 uses a specific verb and resource: 'Read the selected project monthly usage and cost state.' It clearly scopes the operation to project-level billing/usage and separates the daily deployment quota from project usage. It does not explicitly name or distinguish itself from sibling tools such as eurobase_get_project, so it falls 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?

The description implies when to use the tool by explaining that it reads monthly usage and cost state, and it clarifies the default month behavior. However, it does not explicitly state when to choose this tool over alternatives like eurobase_get_project or eurobase_whoami, nor does it provide clear when-not guidance.

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