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

Annotations already indicate this is not read-only, so the description is not burdened with proving mutation. It adds useful behavioral context by framing this as a hidden escape hatch, restricting it to developer/mobile-token usage, and warning against suggesting it for normal login. It could go further in describing what 'linking' changes, but it exceeds the minimum.

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 tight sentences deliver the key constraint first, the usage boundary second, and the alternative routing third. No filler or redundant restatement.

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 fully documented parameter, an output schema, and annotations covering side-effect flags, the description supplies the remaining critical context: when to invoke this tool and which sibling to prefer instead. Nothing essential is missing 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?

The single parameter accessToken is fully described in the schema with coverage at 100%, so the baseline is 3. The description reiterates the same developer/mobile-token restriction but adds no new parameter-level meaning beyond 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?

Description uses a specific verb ('Link') and resource ('Ucode account') and clearly scopes it as a developer/mobile-token-only escape hatch. It also names sibling alternatives (ucode_login_start + ucode_login_poll), distinguishing it from normal sign-in.

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?

Explicitly states when to use: only if the user already has a mobile Bearer token and explicitly asks to use it. It also gives a when-not-to-use instruction and names the exact alternative flow, leaving no ambiguity.

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