user_credentials

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

readOnlyHint=true is already declared, so the '[READ]' tag adds nothing, but with no output schema the description carries the return contract: the object shape (credentials/returned/truncated/secondFactors) and the guarantee that it is 'always the user's complete credential set.' That completeness guarantee is real behavioral context an agent could not infer from annotations.

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?

Front-loaded with the resource and read marker, then Args and Returns in compact form; every line carries information. The '[READ]' prefix is mildly redundant with the annotation, otherwise there is no waste.

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?

For a 2-parameter read tool with no output schema, the description covers what the tool returns, the shape of the payload, and the meaning of both arguments. Missing only alternative-tool routing and any auth/permission expectations for reading another user's MFA configuration.

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 must supply all parameter meaning, and it does for both: user_id is sourced 'from list_users,' and target is defined as an IdP target name from config with an explicit omit-for-default rule. Only marginal detail (valid target values) is missing.

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 first sentence names the exact resource — a user's configured credentials/authenticators — and tags it as 'the MFA surface,' which separates it from sibling user tools like user_sessions, user_lockout_status, and user_detail. It stops short of an explicit verb or sibling comparison, but the scope is unmistakable.

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?

There is no when-to-use guidance or exclusion: nothing says to prefer this over mfa_coverage_analysis, user_detail, or list_users for MFA inspection. The only usage signal is a provenance hint ('from list_users'), which is parameter origin, not tool selection guidance.

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