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

No annotations are provided, so the description carries the full behavioral burden. It does useful work by disclosing that the code is not returned (so the agent must not expect the value back) and that the action happens over CDP on a 'matching page'. It omits major traits for a mutation-style browser action: whether typing submits the form, what happens when no page matches the site, whether existing field content is replaced, and what errors surface.

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 filler, and the primary action is front-loaded. 'The code is not returned' is a compact, high-value caveat that earns its place.

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 4-parameter browser-automation tool with no annotations and no output schema, the definition is minimally adequate. It never explains how the target page is chosen from 'site', what 'selector' overrides, or what failure looks like when no matching page exists – gaps an agent would hit on first 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% – only identity_id is documented in the schema, while site, cdp_url, and selector are bare strings. The description adds no meaning for any of them; 'matching page' gestures at site-based page selection but never defines the matching rule, and 'selector' is never explained at all. With low coverage the description should compensate, and it does not.

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: type the authenticator code into the matching page over CDP. The word 'authenticator' distinguishes it from the sibling fill_email_code, and 'type ... into the page' distinguishes it from get_authenticator_code, which retrieves the code. It stops short of naming an alternative explicitly, so a 4 rather than a 5.

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 the usage scenario (you have obtained an authenticator code and now need to enter it into a page), and 'The code is not returned' hints that get_authenticator_code must be used first to obtain it. However, no condition is stated for choosing this over fill_email_code or fill_login, and no when-not case or prerequisite is spelled out.

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