List database, table, and index sizes

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

Annotations already cover the safe, read-only, and idempotent nature of the tool. The description adds the API endpoint called but does not disclose any additional behavioral traits (e.g., whether results are paginated, any rate limits, or potential errors). The extra context is minimal, leaving the description adequate but not rich.

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 compact with three sentences, but the first two are slightly redundant. Overall, it is front-loaded with the core purpose and efficiently conveys the necessary information without extraneous words.

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?

Given the tool's simplicity and the absence of an output schema, the description adequately covers purpose and parameter. However, it does not hint at the return format (e.g., a list of objects with names and sizes), which would improve an agent's understanding of the output. The openWorldHint annotation partially mitigates this, but the description could be more 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 description coverage is 0%, so the description must compensate. It explains that 'postgresId' identifies the Postgres instance, adding meaning beyond the bare schema. For a single parameter, this is sufficient, meeting the baseline expectation.

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 verb 'List' and the resources ('database, table, and index sizes') and specifies the target ('on a Postgres instance by ID'). It distinguishes the tool from siblings that list other Postgres attributes (e.g., processes, table scans, top queries) by focusing exclusively on sizes.

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 usage for retrieving size information but provides no explicit guidance on when to choose this tool over alternatives, nor does it mention any prerequisites or exclusions. The purpose is clear, but the lack of comparative context limits its helpfulness for tool selection.

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