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

The phrase 'Query discarded' is a useful behavioral disclosure that the input is not retained. With no annotations, the description carries the burden, but it still does not disclose what the tool returns, how it handles an empty or missing query, or whether the other parameters are simply 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 very short and front-loaded, with no filler words. Both sentences add information: the core purpose and the discard behavior. However, it is terse relative to the confusing nine-parameter schema.

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, this is under-specified. An agent cannot determine the return shape, whether only 'query' should be passed, or what happens if multiple parameters 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 each parameter already has a documented meaning. The description adds only the idea that the query is the counted text, which is already stated in the schema's 'Search text; discarded after the length check.' It does not clarify why the other eight parameters exist in this tool's schema.

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 a specific action and resource: 'Count characters in a search query.' This is not a tautology of the tool name. However, it does not distinguish this from sibling length-counting tools like memory-key-count or hn-front-count, and the eight unrelated schema parameters create ambiguity.

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?

There is no guidance about when to use this tool versus alternatives, nor any statement about which parameter to supply. The schema lists nine optional parameters with no direction that 'query' is the relevant one, leaving the agent to guess.

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