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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false. The description adds meaningful context: it returns the same schema payload as named describe tools, accepts two kinds of identifiers, and works for capabilities shipped after a client's cached tool list. This goes beyond the annotations, though it doesn't cover error cases or rate limits.

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 efficient and well-structured: a front-loaded purpose statement, followed by parameter guidance, and ending with usage context. Every sentence carries necessary information and there is no filler.

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?

Though an output schema exists, the description still summarizes the return payload (valid filters, groupings, metrics, detail fields, citation fields). It covers the generic-vs-named tool relationship, parameter choices, and the unique caching scenario, making it complete for the tool's complexity.

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 schema has only a bare 'capability' string with no description (0% coverage). The description fully compensates by specifying valid values: a capability id from list_capabilities_v1 (e.g., 'power.capacity') or a query primitive name (e.g., 'query_power_capacity_v1'). This is essential semantic information.

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: 'Describe any served capability by name' — a specific verb+resource action. It explicitly differentiates itself as 'the generic twin of the named describe tools', distinguishing it from the many sibling describe_* tools.

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 explicit when-to-use guidance: 'Use the generic pair (this + query_capability_v1) when list_capabilities_v1 names a capability that has no named tool in your client's tool list'. It also explains the parameter format (capability id or query primitive name) and the caching rationale, making usage clear.

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