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

Annotations only declare readOnlyHint and openWorldHint; the description adds the substantive traits an agent needs: a 64 KB payload ceiling, kind auto-detection, the exact rule families checked (tabs, duplicate keys, unpinned images/actions, root user, curl-pipe-shell, script injection, committed secrets), optional SARIF output, and a per-call cost of $0.005 USDC. It also documents the failure/retry path for unpaid calls, which is behavior no structured field conveys. The 'POST' wording describes transport for the x402 handshake rather than a state mutation, so it does not materially contradict readOnlyHint.

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 dense sentences, front-loaded with the input formats and max size, then results, then payment mechanics. The rule list is a compact enumeration that earns its space, though the payment sentence is crammed with header names and could be split for readability.

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?

There is no output schema, yet the description specifies the return shape (errors plus common mistakes with line numbers and rule IDs) and the optional SARIF alternative. Combined with the size cap, auto-detection, and the full x402 payment/retry contract, an agent has everything needed to call this correctly on the first attempt.

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 75%, and the description fills the most important gap by noting that kind is auto-detected, which tells the agent the field is optional despite being listed as a property. It also restates the 64 KB bound on content and flags SARIF as optional, but adds nothing about filename or how an explicit kind overrides detection.

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 action (lint) with an explicit enumeration of accepted inputs (YAML, JSON, TOML, .env, Dockerfile, GitHub Actions workflow) and names exactly what comes back (syntax errors and common mistakes with line numbers and rule IDs). That level of specificity separates it cleanly from siblings like json_repair or schema_diff, which operate on different concerns.

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?

The description gives solid operational context for the payment flow (unpaid call returns x402 requirements; retry with X-PAYMENT/PAYMENT-SIGNATURE or params._meta["x402/payment"]), which is genuine when/how guidance. It does not, however, say when to pick this over sibling tools such as json_repair, schema_diff, or x402_lint, leaving that comparison to inference.

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