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

With no annotations, the description carries the full burden and does reasonably well: it discloses that values are flattened to strings, that the body is returned alongside the pairs, and the no-block edge case. It omits failure behavior for malformed YAML and only hints at the x402 payment model via the '5 free trial calls per signed wallet' note.

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?

A single front-loaded sentence that leads with the operation and its return contract; the trial-call note is tacked on at the end and the redundant 'Markdown Frontmatter:' label adds minor noise, but overall it is tight and readable.

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 or annotations, the description covers the return contract reasonably but leaves the three undocumented parameters completely unaddressed. For a tool whose input routing is ambiguous, that gap keeps it at minimum-viable completeness.

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?

Three string parameters (md, text, input) exist at 0% schema description coverage, and the description never names or distinguishes them. The agent can infer that the argument is markdown source text, but cannot tell whether the three are aliases or which one to populate, which invites incorrect invocation.

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 (Parses) and resource (leading --- frontmatter block) and even names the return shape: flat string key-value pairs plus the remaining body. Among the many x402-markdown-* siblings, this scope is unambiguous, so an agent can select it without opening the schema.

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 explains what happens but never says when to reach for this tool versus alternatives such as x402-markdown, x402-markdown-html, or x402-frontmatter-adjacent utilities. The only conditional given ('without a block hasFrontmatter is false') is behavioral, not a usage rule, and no prerequisites or exclusions are stated.

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