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

With no annotations, the description carries the full burden, and it does disclose a non-obvious behavioral trait: per-call billing that only charges on business success and auto-refunds on content violation, model timeout, or generation failure. It also enumerates the deliverable (root cause, patch, verification steps), which effectively stands in for a missing output schema. It does not cover latency, retry semantics beyond the schema's requestId, or limits on output size.

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 with zero filler: the first is the input→output contract, the second is the billing/refund policy. The core capability is front-loaded before the commercial detail.

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 4-parameter tool with one required field, full schema coverage, and no output schema, the description covers both what the tool produces and how billing behaves. Missing only minor operational details such as expected turnaround or output size limits, which are unlikely to change how an agent invokes it.

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 all four parameters including the requestId idempotency key and the 6000-character error limit are already documented. The description only restates that error and code are the core inputs and adds nothing about format or syntax. Baseline 3 is appropriate when the schema does the heavy lifting.

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 gives a concrete input→output contract: error stack plus code in, root-cause localization, minimal fix patch, and verification steps out. That is far more specific than a name restatement and clearly separates it from sibling generators like codegen or codeexplain. It stops short of naming a sibling, so 4 rather than 5.

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?

Usage is only implied by the input contract — an agent infers it should call this when it has an error stack to diagnose. There is no explicit 'use this instead of codeexplain when…', no preconditions, and no exclusions. The billing sentence adds cost awareness but not routing guidance.

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