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

Annotations already declare readOnly, idempotent and non-destructive, so the safety profile is covered. The description adds genuinely new context: the response is metadata only and never exposes secret values, which tells an agent it is safe to surface results to a user. It stops short of noting any permission requirements or output shape.

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?

Two short sentences, zero filler, with the core purpose front-loaded and the security caveat immediately after. Every sentence earns its place.

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 parameters, no output schema and full annotation coverage, the description carries little burden. It discloses the one thing an agent can't infer from structured fields — that secrets are never returned — though it could say slightly more about what 'metadata' includes (provider names, status, timestamps).

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 no parameters, so the baseline is 4. Nothing in the schema needs compensating for, and the description correctly avoids inventing filtering options that don't exist.

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: lists configured provider credentials, which is clearly distinct from sibling list_api_keys or list_numbers. It does not explicitly name an alternative, but the resource is unambiguous enough that an agent can place it without opening the 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 implied by the verb — call it when you need to see which providers are configured — but there is no explicit when-to-use, no exclusions, and no reference to alternatives such as list_api_keys for related credential inspection. For a zero-parameter read tool this is acceptable but thin.

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