Sign in with a cookie file

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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), so the bar is lower. The description adds meaningful context beyond them: the fallback role, the credential-handling restriction, and the origin of the file. It does not describe what happens to the existing session or how failures 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?

Three sentences, front-loaded with the when-to-use condition, then the operational instructions, then the safety constraint. No sentence is filler and nothing is repeated from the schema or annotations.

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 credential-import tool with no output schema and full schema coverage, the description covers trigger, input provenance, and a security guardrail. It omits post-success behavior (session replacement, validation failures), which would matter for an auth-mutating operation.

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 100%, so the baseline is 3, but the description adds real value by enumerating the acceptable file contents/formats (DevTools cookie header paste, cookie-extension JSON export, cookies.txt), which tells the agent what filePath may legitimately point to. It also enforces a security rule about never requesting raw cookie values in chat.

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 action (sign-in) and mechanism (cookie file import) and frames itself as the fallback path, which is precisely what separates it from the browser-based login siblings. An agent can tell when this tool applies without inspecting any 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 condition for use is explicit: 'Fallback sign-in when the browser window cannot be used.' It also tells the agent how to instruct the user to produce the file. It stops short of naming axcel_login_begin/axcel_login_complete as the primary alternatives, so the routing is implied rather than spelled out.

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