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

Annotations only declare readOnlyHint and openWorldHint; the description adds real value beyond them by disclosing the return payload (download URL, name, size, formats) and the cost model ('2 credits, charged only when a call succeeds'). It does not mention size limits, failure modes, or that 'web' sources are HTML-only without JavaScript (that detail lives only in the schema).

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?

Four tight sentences: purpose first, then return value, then usage and alternatives, then cost. Every sentence carries distinct information with no repetition of the title or schema.

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?

No output schema exists, yet the description still summarizes the return shape (URL plus name, size, formats), and the schema fully documents inputs. Combined with the sibling routing and cost note, nothing an agent needs 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 coverage is 100%, so file_url, source_format, and target_format are already described in detail in the schema (including the web/HTML caveat and the ConvertAPI fallback). The description adds only illustrative pairs, not syntax or constraint detail, so 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?

Specific verb+resource: 'Convert documents, web pages, spreadsheets and images between formats.' Concrete examples (Word to PDF, PDF to Markdown) and explicit disambiguation from the 'documents' and 'scrape' siblings make it unmistakable.

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?

States when to use it ('to change a file's format') and names two alternatives with the conditions that select them: 'To extract specific fields use documents; to read a web page's text use scrape.' Nothing left to inference.

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