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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered, and the description adds genuinely non-obvious behavior: the payment/settlement model, the 1000 KB JSON body limit, that output arrives as a string in the content field, and that SIE4 is experimental. It stops short of describing error payload shapes or detection fallbacks, but this is well above the annotation baseline.

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 with the cost and payment requirement front-loaded, followed by output format, size cap, and settlement semantics in a logical order. The leading 'Paid ($0.005):' fragment is slightly abrupt but earns its place by signaling cost immediately.

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 14-parameter tool with no output schema, the description covers the two things an agent could not infer from the schema: where the converted file appears (a string in the content field) and how the paid invocation settles. It omits behavior around auto-detection failures and the trade-offs of the experimental SIE4 format, but the essential call contract is present.

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 every one of the 14 parameters is already documented in the schema and the description is not obligated to compensate. It reinforces the `to` enum by listing the same four target formats and hints at size constraints relevant to `content`, but adds no new syntax, defaults, or interaction rules beyond the structured fields.

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 names a specific action and resource ('Parses a statement and exports it') and enumerates the concrete output formats (normalized CSV, hledger journal, SIE4, JSON), so the agent knows exactly what it produces. It never names the sibling tools (parse_statement, analyze_statement) that could plausibly overlap, so differentiation is left to inference.

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 payment (cost of $0.005, failed 4xx/5xx calls are not settled, missing payment header returns x402 requirements), which tells the agent when it will even succeed. However, it offers no guidance on when to choose this tool over parse_statement or analyze_statement, so the routing decision is only implied.

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