user_credentials

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

No annotations exist, so the description carries the burden. It opens with '[READ]' to indicate a safe read operation, and explicitly states return behavior including 'truncated': false and 'always the user's complete credential set.' This adds valuable behavioral detail beyond the schema.

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 and front-loaded with '[READ]'. The argument list is concise, and every sentence contributes necessary information—purpose, parameters, and return format—with no fluff.

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?

Despite having no output schema, the description provides the return structure and notes the invariant of returning the complete credential set. For a simple 2-parameter read tool, this is complete and gives the agent enough context to invoke correctly.

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%, but the description fully compensates: it explains that user_id comes from list_users and that target is an optional IdP target name with a default behavior. Both parameters are given meaningful context beyond raw schema fields.

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 uses a specific verb+resource: '[READ] A user's configured credentials/authenticators — the MFA surface.' It clearly identifies the tool's function and differentiates it from sibling tools like user_detail by focusing on MFA 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?

Clear usage context is provided: 'user_id: User id, from list_users' and 'target: IdP target name from config; omit for the default.' It does not explicitly name alternative tools, but the read-only scope and parameter provenance make when-to-use reasonably clear.

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