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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavioral context beyond the annotations: the single error mode (not_found), that its message enumerates all valid names, and that the guide's return payload includes error-recovery and worked examples. It stops short of describing size or latency characteristics.

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?

Front-loaded with the payload and the trigger condition, then packed with actionable detail. Minor waste in the self-referential tail ("Full guide: get_tool_guide or /agent/tools.json#get_tool_guide") and the repeated catalogue pointer, which cost it the top score.

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 no output schema, the description compensates by enumerating the guide's full contents (summary, when to use, what not to use, parameters, caveats, outputs, error recovery, worked examples) plus the error and next-step behavior. Nothing an agent needs in order to call this correctly is missing.

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% and both parameters are documented there, including the null case for tool_name and the non-authority caveat for shopping_session_id. The description only adds an example invocation ({"tool_name":"create_checkout"}) and does not restate or extend the null-list behavior, so the baseline of 3 applies.

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 verb (returns/reads) and resource (the complete guide for one RoboTrunk tool), and enumerates the guide's contents, so an agent knows exactly what comes back. It is clearly distinguishable from every sibling, all of which act on products, checkouts, or watches rather than on tool metadata.

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 it ("about to call a tool for the first time and want more than its short description") and gives the follow-up step ("call the tool you read about, feeding an example's input straight back in"). It also covers the error path: not_found is the only error and its message lists every valid name.

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