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

The description adds one behavioral note: 'Query discarded.' However, with no annotations and no output schema, it does not disclose the return format, how multiple parameters are handled, or why nine unrelated string parameters are accepted. The agent is left guessing about observable behavior beyond the disposal fact.

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 with no filler. The behavioral note 'Query discarded' earns its place, and the main action is front-loaded.

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 tool with nine optional parameters, no annotations, and no output schema, the description is too thin. It does not clarify which field represents the search query, what the return value looks like, or how the tool behaves when multiple fields are supplied.

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 parameters are already documented individually. The description itself adds no parameter-level meaning beyond the schema, and it even creates mild ambiguity by referring to 'a search query' while the schema includes url, city, feed, host, json, and other unrelated 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 states a clear action ('Count characters') and a resource ('a search query'), so the core purpose is understandable. It does not explicitly differentiate from sibling tools like memory-key-count or calc-eval, but the verb and resource are specific enough for a 4.

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 no guidance about when to use this tool versus alternatives, and no conditions or exclusions are mentioned. The intended use case is only implied by the tool name, not explained.

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