cookie_set

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

No annotations are provided, so the description must disclose behavioral traits itself. It does so by revealing the non-obvious Firefox session-cookie behavior: expires_days=0 keeps the cookie in memory only and it is lost after browser_close even though the profile persists. This is valuable behavioral context beyond the basic action.

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 two sentences with no filler. The core action is front-loaded, and the important caveat is placed immediately after. Every sentence 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 mutating cookie tool with no annotations and no output schema, the description provides the essential operational context: how to set a cookie and how to control its lifetime. It does not discuss overwriting behavior or domain/path constraints, but the critical persistence scenario is covered well enough 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 38%, and the description compensates for the most subtle parameter by explaining what expires_days means in practice and giving an example value. The remaining parameters (name, value, domain, path, secure, same_site) are either self-explanatory or already described in the schema.

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 states a specific verb and resource: 'Set a cookie.' This immediately distinguishes it from sibling tools like cookie_delete, cookie_list, cookie_import, and cookie_export. An agent can understand the tool's core function without opening the schema.

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 provides clear, practical guidance on how to achieve a persistent login session ('Pass expires_days (e.g. 30)') and warns about the default session-cookie behavior. It does not explicitly name alternative cookie tools, but for a simple set operation the context is clear.

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