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

With no annotations, the description carries the disclosure burden. The phrase 'Query discarded' is a useful side-effect disclosure, but it does not clarify whether any other supplied fields are ignored, whether the query is executed anywhere, or whether there are other behavioral implications beyond discarding the input.

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 extremely concise: two short sentences with no filler. The primary action is front-loaded, and the side-effect note earns its place.

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?

No output schema and no required parameters create gaps: the description does not specify the return format of the count or confirm that `query` is the intended input. The large set of optional parameters is unacknowledged, though each schema entry helps clarify that the others are discarded.

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 schema already documents every parameter. The description adds no extra parameter semantics beyond loosely referring to 'a search query', which maps to the `query` parameter but provides no new insights.

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'), clearly distinguishing this from sibling counting tools like hn-front-count and memory-key-count. It is not a tautology and leaves little doubt about the tool's core function.

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 implies usage: when an agent needs the character count of a search query, this is the tool. However, it offers no explicit guidance on when not to use it or which sibling alternatives might be more appropriate for related tasks.

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