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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely non-obvious behavior: the 82-language coverage, the output code systems, Chinese script disambiguation, and — importantly — the cost model (10 free calls/day, then $0.001/call) plus the two payment mechanisms. That pricing/rate-limit disclosure is exactly the kind of context annotations cannot carry.

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?

Front-loaded with the purpose and coverage in the first clause, with cost/payment details trailing. It is dense but nearly every clause carries information; the '[served by tools.moneytools.dev]' tag and the parenthetical payment plumbing are the only slightly noisy elements.

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 one-parameter detection utility with an output schema and full annotation coverage, this is complete: purpose, supported language count, output code standards, script-level nuance, and the cost/auth model are all present. Nothing an agent needs in order to call it correctly or anticipate billing 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 description coverage is 100% with a single required 'text' parameter that already carries an example and a length hint, so the schema does the heavy lifting. The description adds only indirect meaning (that the text will be mapped to one of 82 languages) and gives no format/length guidance of its own. Baseline 3 is appropriate.

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 ('Detect the language of a text') and immediately bounds the scope with concrete facts: 82 languages, ISO 639-3 + BCP 47 output, and Traditional vs Simplified Chinese disambiguation. No sibling in the catalog performs language detection, so no sibling differentiation is required, and an agent can tell exactly what this does.

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?

Usage is implied by the purpose statement — call it with text to identify a language — but there are no explicit when-to-use/when-not conditions or named alternatives. The only routing-style guidance is about payment paths (x402 vs X-API-Key), which is invocation mechanics rather than selection guidance.

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