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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the bar is lower. The description nonetheless adds real value beyond them: it discloses that secrets are never returned ('never passwords') and that results are paginated with a has_more indicator — neither of which the schema conveys.

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 sentence, front-loaded with the verb and resource, that still packs in the security caveat and the pagination model. No filler clauses to cut.

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?

There is no output schema and no annotations gap to fill, and the description covers the essential return contract (key names only, plus has_more for paging). Slightly incomplete on what a key object contains and what happens on an invalid agent_id, but adequate for a simple paginated list.

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 carries the burden, and it does name the limit/offset bounding and the has_more signal. It does not explain agent_id beyond the possessive 'agent's', nor the 1-100 limit cap or default paging behavior, leaving the required parameter essentially to the schema's type constraints.

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 (List) and resource (a workspace AI agent's named PBX keys) with scope clarified by 'never passwords'. The verb alone separates it from the sibling create_pbx_key, revoke_pbx_key and rotate_pbx_key, so an agent can route correctly without opening a schema.

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?

Usage is only implied by the 'List' verb and the agent scoping; there is no explicit when-to-use statement, no prerequisites, and no pointer to create_pbx_key/revoke_pbx_key for the non-read paths. 'Never passwords' hints that secret retrieval happens elsewhere but does not name an alternative.

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