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

Annotations already signal read-only, idempotent, non-destructive. The description adds user-mediated flow: returns a URL the user can open to grant access, making the deferral of action clear. It doesn't mention permissions or waiting behavior, but the key non-mutating behavior is disclosed.

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 sentences; first sentence gives the trigger condition and action, second gives the outcome. No filler.

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?

With one optional parameter, readable output schema, and clear trigger condition, this is nearly complete. It does not mention what happens after the user grants access or that access may be delayed, but for such a simple tool the description covers the essential flow.

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?

One parameter is fully documented in the schema (100% coverage). The description adds no extra semantic beyond 'shown to the user', which is already in the schema, so baseline 3 is appropriate.

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 uses a specific trigger ('when a user wants you to access a file that isn't in the file list'), a clear action (call this tool), and states the outcome (returns a URL for the user to select and grant access). This clearly distinguishes it from siblings like access_file_by_url or list_files.

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?

Provides an explicit when-to-use condition ('file isn't in the file list') and implies you should not use it for files already in the list, but does not explicitly contrast with alternative tools or state when not to use it.

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