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

Annotations already declare a destructive write (readOnlyHint=false, destructiveHint=true); the description adds genuinely new behavior by stating the secret itself is never returned — only metadata, or a local CLI command for the local_value path. It does not explain why the operation is destructive (overwrite of an existing non-active value?) or how expected_version conflicts are surfaced, which are the remaining gaps.

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?

Three short sentences, front-loaded with the action and immediately followed by the alternative. The two consecutive 'Returns ...' sentences read slightly stitched together, but each carries distinct information (no secret leak vs. CLI handoff).

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 destructive, open-world, 7-parameter mutation with no output schema, the description does cover the return shape, which is valuable. It leaves out permission/scope requirements, the meaning of the required expected_version check, and the interaction between idempotentHint=false and the idempotency_key parameter, leaving an agent under-informed for safe invocation.

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 86%, so names, enums, and patterns are already documented; the description only reinforces the source enum semantics (doppler saves a reference, local_value returns a CLI handoff). It adds nothing about expected_version's concurrency role or when to supply idempotency_key, so the baseline 3 holds.

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 states a specific verb (Save) and a precise resource scope (one selected credential value or Doppler reference), which distinguishes it from the list-only credentials tool. It also signals the branch between a stored reference and a local value, though the only named alternative (credentials.replace) is not actually present in the sibling list, which could send an agent looking in the wrong place.

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?

It gives one explicit exclusion with a named alternative: replacing an already-active credential belongs to credentials.replace, not here. It lacks positive when-to-use context (e.g. first-time setup vs. rotation) and any prerequisite note about expected_version or idempotency, so a single clear boundary is present but the guidance is not complete.

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