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

With no annotations, the description carries the transparency burden. 'Query discarded' does signal a no-retention, non-side-effecting behavior, and the schema repeats this for the 'query' parameter. However, the description does not disclose the return value, behavior when 'query' is absent, or whether the unrelated parameters are ignored.

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 two short sentences, front-loaded with the action and the key side-effect note. There is no filler, repetition, or irrelevant detail.

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?

The tool has nine optional parameters, no annotations, and no output schema, so the description must provide more operational context. It omits what the tool returns, which parameter to pass, and how the other eight parameters are handled, leaving an agent with genuine ambiguity.

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 structured fields already document each parameter, establishing the baseline at 3. The tool description adds no parameter-level guidance, leaving the agent to infer that only 'query' is relevant to the length count.

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 states a specific verb ('Count') and resource ('characters in a search query'), so the core action is clear and matches the tool name. However, the nine-parameter schema includes many unrelated fields with no explanation of their relationship to the search query, which prevents a higher score.

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 use case is implied: call this when a character count for a search query is needed. There is no explicit statement of when not to use it, no named alternative among the sibling shape/count tools, and no guidance on which of the nine optional parameters should actually be supplied.

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