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

Annotations already declare readOnlyHint, openWorldHint=false, idempotentHint, and destructiveHint=false, carrying the safety profile. The description adds the scoping fact that values are per-provider, which is useful, but doesn't mention date-range effects or whether results are paginated/capped.

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?

One efficient sentence, front-loading the action and the key dimensions, then adding the routing hint. 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?

For a read-only discovery tool with annotations covering safety and no output schema, the description is adequate but incomplete: it doesn't clarify the date-range parameters' role, the provider-id requirement (beyond schema), or returns. The partial dimension list is a notable gap for an enum-driven tool.

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 25%, low enough that the description should compensate. It names the dimension parameter and gives example values, but the parameter list is incomplete versus the enum (missing identity, namespace, workload, cluster, resource_id). start_date/end_date and cost_source_id receive no semantic help from the description beyond what the schema says.

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?

Clear verb+resource: 'List the distinct values seen for a given dimension ... for one provider.' However, it only lists 5 of the 10 enum dimensions, potentially misleading about scope. It does distinguish from query_costs by noting it's for discovery beforehand.

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?

Explicitly states 'useful for discovering filter values before calling query_costs', which gives a clear when-to-use and names the alternative. No when-not-to-use or exclusions, but strong context.

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