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

Annotations already indicate a destructive, non-read-only operation. The description adds useful behavioral constraints: the session must be a standalone Gate session and the UID must come from the OAuth login result. It doesn't elaborate on what happens if a binding already exists, but the annotation's destructive hint partially covers this, and the added OAuth constraint goes beyond annotation info.

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 extremely concise: two short sentences with the action first, followed by a condition and a pointer to the alternative. Every word adds value, 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?

For a 2-parameter tool with full schema coverage and no output schema, the description covers the core purpose, a key precondition, and the alternative for rebinding. It doesn't explicitly mention the required mcp_token, but that is in the schema. The only minor gap is a lack of detail about failure behavior or existing bindings, but overall it's sufficient for an agent to use the tool correctly.

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 schema already explains both parameters thoroughly. The description reinforces the gateUid constraint but doesn't add new parameter meaning beyond what the schema states. 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 clearly states the action: 'Bind Gate exchange UID to session' with a specific verb and resource. It also distinguishes itself from the sibling tool 'replace_binding' by noting that rebinding is handled there, making the purpose unambiguous.

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 provides explicit usage conditions: 'Standalone Gate session only' and 'gateUid must equal login_result.gate_uid from Gate OAuth'. It also names the alternative for rebinding ('→ replace_binding to rebind'), giving clear guidance on when to use this tool vs. its sibling.

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