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

Adds substantial behavior beyond annotations: the value is encrypted, existing names are overwritten, username/url/note are exposed in vault_list, bot ACLs restrict readability, and cost is $0.001 per call with no charge on failure. The only gap is that overwriting is not framed as destructive or confirmed as irreversible. The 'replaces it' wording is arguably idempotent, which sits at odds with idempotentHint=false, but this is a conservative annotation rather than a real contradiction.

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?

Four short sentences, front-loaded with what is stored and where, then overwrite behavior, visibility, access control, and cost. No filler; every clause adds a fact the agent would otherwise have to guess.

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?

No output schema exists, and the description covers the full operational picture an agent needs: encryption, replacement semantics, which fields become visible, read-access scoping for bots, and billing. Nothing material is missing for correct 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 only 33%, so the description must compensate, and it does: it explains that value is the secret material encrypted at rest, that username/url/note are non-secret metadata surfaced by vault_list, and that bots narrow read access. Name is only lightly covered relative to the schema's pattern example, leaving a small residual gap.

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 ('Keep a secret ... encrypted in the account's vault under a name') and distinguishes itself from the read path by naming vault_get for retrieval. It also implicitly separates the secret value from non-secret metadata that appears in vault_list.

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?

Clearly signals the save-then-read workflow by pointing at vault_get, and warns that reusing a name replaces the existing entry, which is the main usage pitfall. It does not explicitly exclude alternative tools (e.g., vault_generate_password for creating a secret), so it stops short of full when/when-not guidance.

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