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

With no annotations, the description does most of the work by disclosing that the secret is encrypted and is not returned, which is meaningful behavioral context for a credential-storing tool. However, it does not say whether existing logins are overwritten, whether the operation is idempotent, what permissions or identity are required beyond the schema note, or what the response contains.

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?

Two short sentences with no wasted words. The core action is front-loaded, and the secret-handling caveat follows immediately.

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?

This is a four-parameter mutation tool with no annotations, no output schema, and only partial parameter documentation. The description adds one useful behavioral fact about the secret but leaves too much unsaid about overwrite behavior, identity requirements, and the result of the call.

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 only 25%; identity_id is documented in the schema, but site, username, and secret have no semantic explanation in the description or schema. The description mentions 'secret' but only to explain its handling, not its format or parameter semantics, so it fails to compensate for the low 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?

The description gives a clear verb and resource: 'Store a site login.' An agent can tell this saves credential records rather than sessions or authenticator entries, though the sibling tools save_session and save_authenticator are not explicitly contrasted.

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 guidance on when to use this tool versus save_session, save_authenticator, or fill_login. The only implied usage is that a login is being persisted, but no prerequisites, exclusions, or alternatives are stated.

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