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

The readOnlyHint annotation already signals a safe read operation, and the description adds useful behavioral context by specifying what is included ('specs and AI drafts') and the fallback scoping to the address. This goes beyond the annotation without contradicting it.

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 sentence that front-loads the core purpose and adds only the necessary scoping detail. There is no redundant language or repetition of the name or title.

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 no-parameter, read-only usage lookup, the description is nearly complete: it names the data returned and the scope. It doesn't describe the exact return shape, but with no output schema and a simple resource, the provided context is sufficient for an agent to invoke the tool correctly.

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 accepts zero parameters, so there are no parameter semantics to document. The description correctly explains what the tool reports, and with schema coverage at 100% there is no hidden parameter information an agent would miss.

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 identifies the resource ('plan and quota usage') and scopes it to the API key or address, and it is easy to distinguish from the sibling tools which operate on different resources. It lacks an explicit imperative verb, but 'Current plan and quota usage' is unambiguous enough.

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 provides clear context for when the tool applies: it reports usage for the API key, or for the address when no key is set. It does not explicitly name alternatives or exclusions, but the sibling tools are distinct enough that an agent is unlikely to confuse them with a usage lookup.

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