browser_autofill_login

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

With no annotations present, the description carries the disclosure burden. It clearly states the core behaviors—filling and submitting a login form—and the credential source, but it does not explain failure behavior, side effects of form submission, or what happens when optional selectors are omitted.

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 a single well-structured sentence that front-loads the core action. It contains no filler or unnecessary detail.

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?

The description is adequate but incomplete for a tool with 5 parameters and no output schema or annotations. It does not explain the significance of optional selectors, the behavior when submitSelector is missing, or expected outcomes after the submit action.

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 100%, so the parameters are already individually documented. The description adds high-level purpose but does not clarify how usernameSelector and submitSelector interact with the core behavior, such as whether password-only filling is possible.

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 specific verb and resource: automatically fill and submit a login form using Keychain-stored credentials. This clearly differentiates it from sibling tools like browser_type, keychain_store_credential, and passkey_save_registration.

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?

The description implies a prerequisite: credentials must already exist in macOS Keychain, and that suggests when this tool applies. However, it gives no explicit when-to-use versus when-not-to guidance and does not mention alternatives such as browser_type or passkey flows.

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