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

With no annotations, the description carries the full transparency burden, but it only repeats the schema-level detail that the query is discarded. It does not explain what happens to the eight other unrelated schema parameters, whether they are ignored or rejected, or what the exact return value is. Since the schema already documents 'discarded after the length check', the description adds little behavioral value beyond structured fields.

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: 'Count characters in a search query. Query discarded.' The action is front-loaded, and every word contributes either to purpose or behavioral 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?

Despite being a simple operation, the tool has a large 9-parameter schema, no output schema, and no guidance on which parameters are actually needed. The description does not reconcile why fields like `city`, `feed`, `host`, `json`, and `path` are present when the tool only counts characters in a query. An agent could be misled about how to invoke the tool correctly.

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 and the description is not required to compensate. The description's mention of 'search query' roughly maps to the `query` parameter, but it adds no new semantic details beyond what the schema already says. It also fails to clarify that the other parameters are irrelevant to this tool.

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 clearly states the core operation: count characters in a search query. It is specific about the verb ('Count') and resource ('characters in a search query'), so it avoids tautology. However, it does not explicitly differentiate itself from sibling length/count-type tools like memory-key-count or hn-front-count.

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 provides no explicit guidance on when to use this tool versus alternatives, nor any exclusion or prerequisite. An agent must infer the sole usage case from the purpose statement alone. This is below the bar for clear usage guidance.

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