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

Annotations cover read-only and open-world traits, but the description adds substantial context beyond them: pricing ($0.03 USDC via x402 or prepaid credits), free-trial availability, that paths/line numbers are stripped, that accepted answers are read in full, and that it honestly reports when nothing matches. It does not contradict any annotation.

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 core workflow is front-loaded in the first sentence and the operational notes follow. Slight redundancy: the $0.03 price appears in the title and again in the description body, costing a little efficiency.

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?

An output schema exists, so return values need not be enumerated, yet the description still characterizes the output (likely cause, concrete fix steps, cited sources, plain no-match statement). Combined with input guidance and pricing, an agent has everything needed to call it 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 coverage is 100% and the schema already documents library, message (including the stripping behavior), and the ecosystem enum. The description only restates 'optionally the library' and adds no syntax or format detail beyond the schema, so the baseline 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 and resource (explain and fix an error) plus the mechanism: finds matching GitHub issues and Stack Overflow questions, reads accepted answers, and writes cause + fix steps with citations. It also differentiates from the sibling error-known by describing the relationship ('like /error/known').

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?

Gives clear invocation context ('Paste the error (stack traces fine) and optionally the library') and implicitly routes the known-error lookup case to /error/known. It does not explicitly state when NOT to use it or contrast it head-to-head with siblings beyond the parenthetical reference.

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