filter_languages

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

Annotations already carry the safety profile (readOnly, idempotent, non-destructive), so the description's value is the added semantics it does supply: matches are counted against the denominator of languages coded for ALL conditions, and results include family/genus breakdowns and top contributing families. That denominator detail is genuinely non-obvious and affects interpretation. It does not discuss cost or performance of broad filters.

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?

Two sentences, front-loaded with the purpose and followed by the return semantics. No filler, no restatement of the tool name.

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 an output schema present and full parameter coverage, the description only needs to frame the query model, which it does via the denominator explanation. Minor gap: it never notes the 8-condition cap or how the limit parameter interacts with the always-complete counts, though the schema covers both.

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 the baseline is 3. The description reinforces the AND semantics and gives an illustrative feature pairing, but adds no format, precedence, or interaction detail (e.g. how family/sample/macroarea intersect with conditions) beyond what the schema already documents.

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+resource ("Find languages matching feature conditions") and immediately grounds it with a concrete example (SOV order AND postpositions), which makes it distinguishable from find_language (single lookup) and language_profile. It stops short of naming a sibling to route away from, so it misses the 5 bar.

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 example implies the intended scenario (multi-feature filtering), but there is no explicit when-to-use/when-not guidance and no mention of how this differs from crosstab, which is the obvious alternative for multi-feature queries. Usage is inferable rather than stated.

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