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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so safety is covered. The description adds genuinely new context: exactly which fields are returned and the security guarantee that 'the key itself is never returned' — a disclosure an agent could not infer from structured fields.

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?

A single dense but front-loaded sentence pair: the [read] tag, the purpose, the returned fields, the downstream use, and the security note. No filler, no repetition of the 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?

With no output schema, the description compensates by enumerating the returned fields, which is the key missing piece for an agent. Minor gaps remain: it doesn't say what happens when the caller has no qualifying accounts, nor whether the list is paginated or ordered.

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 takes zero parameters, so the baseline is 4. The description correctly spends its words on output semantics instead of inventing parameter guidance, which is the right allocation for a no-arg tool.

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?

States a specific verb and resource ('list ... Google service accounts that can run `search_gservice_maps`') and scopes it with a qualifier (accounts holding a service-account key). This clearly separates it from sibling listers such as list_gservice_indexer, list_gservice_query and the search tool itself.

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 links the output to the downstream action: 'pass either id to `search_gservice_maps` to pick the account', which tells the agent when this tool is a prerequisite. It stops short of stating exclusions (e.g., that this is not for querying Maps data itself), but the context is clear.

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