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

The description states 'Local, no outside service,' which directly contradicts the annotation openWorldHint=true. Although it otherwise adds useful behavioral context such as pricing, short-text limitations, and non-mutating behavior, the explicit contradiction with a structured annotation triggers a score of 1.

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?

The description is front-loaded with purpose and return format, then moves to limitations, usage, example, and pricing. It is somewhat long for a one-parameter tool, and the final sentence partially repeats pricing/read-only information, but most sentences carry useful context.

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, but the description explains the return shape in detail: most likely language, ISO codes, English name, and ranked candidates with relative scores. It also covers input-length caveats and the 'und' outcome, leaving no major gap for correct invocation.

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 the baseline is 3. The description adds practical semantic guidance beyond the schema by noting that detection works best above about 20 characters and that very short or mixed text returns 'und,' which helps an agent interpret the single text parameter.

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 opens with a specific verb and resource: 'Detect which language a text is written in.' It also explains the exact return content (most likely language, ISO 639-3/639-1 codes, English name, candidates with relative scores) and the underlying engine, making it clearly distinguishable from sibling text utilities.

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?

It gives concrete use cases: routing messages, picking a translation target, and filtering content by language. It also warns that very short or mixed text returns 'und,' but it does not name alternative tools or state explicit when-not-to-use conditions.

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