Import cookies into a browser profile

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

Beyond the annotations (destructiveHint=true, openWorldHint=true), the description discloses that cookies are encrypted with the profile's key before storage, are never returned by any endpoint, that confirmation is required for this exact account operation, and that runs can spend credits or trigger downstream actions. This is exactly the extra behavioral context annotations cannot carry.

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 purpose and the key url/no-url behavior are front-loaded, and each paragraph covers a distinct concern (import semantics, then confirmation/credit risk). It is slightly dense and the url explanation duplicates the schema text, but nothing is wasted.

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 complex tool (8 params, nested payload object, no output schema) it covers the critical ground: mutating/destructive nature, encryption and non-return of secrets, confirmation requirement, and credit/spend risk. The various body-flag vs payload vs payload_file alternatives are left to the schema, but that is reasonable given the schema already documents them fully.

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 baseline is 3. The description restates the `url` semantics and the `default` profile_id hint that already appear in the schema, adding only marginal meaning (e.g., default profile is created if needed). It does not add syntax or format detail beyond the structured fields.

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 opens with a specific verb+resource ('Add sign-in cookies to a browser profile') and even identifies the underlying CLI command it maps to, leaving no ambiguity about what the tool does. No sibling tool operates on browser-profile cookies, so the agent can immediately tell this apart from list_browser_profiles or the many unrelated siblings.

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 clear conditional behavior: with `url` only that site's cookies are kept and replaced, without it every site in the payload is imported, plus the `default` profile_id convention. It also flags that explicit confirmation is required and warns against auto-resubmitting unknown outcomes. It stops short of naming an alternative or a 'when not to use' boundary, but the operative conditions are spelled out.

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