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

Annotations already declare readOnlyHint=true, and the description reinforces it while adding genuinely useful behavior: secret values are never returned, and each entry carries identity, availability, and sync state. The installation_id detail for GitHub App credentials adds real, non-obvious context. It stops short of describing pagination or exact return 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?

Scope is front-loaded in the first clause, and each sentence adds information. The jump to the installation_id aside is slightly tangential for a top-level description, but it is relevant to a consuming workflow and does not bloat the text.

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 responsibly summarizes returned data (identity, availability, sync state) and the security guarantee about secrets, which is what an agent needs before calling. For a single optional-parameter read tool this is nearly complete, missing only pagination/volume expectations.

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 100% and the provider parameter's schema description already enumerates every valid value, so the schema carries the semantics. The description's examples ('github', 'hetzner', 'ssh-key') add minor reinforcement but no new meaning, matching the baseline for full coverage.

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 (every credential) with explicit scope: 'across all providers (git, helm, cloud providers, SSH keys, legacy aws/gcp)'. This scope statement is exactly what distinguishes it from siblings like list_provider_credentials, list_gitops_credentials, and list_helm_registry_credentials.

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 'across all providers' framing implies this is the broad inventory versus the provider-specific siblings, and the note about installation_id feeding related-repositories tools gives downstream context. However, it never explicitly names an alternative or states when to prefer a narrower tool, so usage is left to inference.

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