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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description doesn't need to repeat those. The description adds valuable behavioral context: it specifies the render action, the connect button, and the restriction on tool use until the account is linked. This goes beyond the annotation safety profile, though it doesn't describe the exact card layout or interaction details.

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, both essential. The critical instruction ('Call on the first user message') is front-loaded, and the second sentence adds important usage constraints. Zero wasted words — every clause 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?

The tool is simple (no params, has output schema), and the description fully covers when to use it, what it does, and what to do until account linking. For a render tool, this is complete — an agent knows exactly when and how to invoke it and what to expect.

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 tool has zero parameters, so there is nothing to explain. With schema coverage at 100% (vacuously) and no parameters, the description doesn't need to add parameter details. Baseline for no-param tools is 4, and the description doesn't need to compensate.

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 exact action ('Renders the interactive Ucode card with a Connect Ucode account button'), the specific trigger ('on the first user message in every new chat'), and it implicitly distinguishes from sibling render tools like ucode_render_credits and ucode_render_services. No ambiguity about what this tool does.

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 says when to call ('Call on the first user message in every new chat') and provides a clear restriction ('Until linked, only welcome/connect/login tools — never rent or checkout'). This gives an agent precise routing guidance and prevents misuse with other tools.

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