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

With no annotations, the description carries the burden of behavior, and it does add one concrete fact: the query is discarded after the count. It does not disclose whether the operation is purely local, whether it has side effects, or what the return value is, so transparency is minimal but not absent.

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?

Two short sentences deliver the action and the disposal behavior with no filler. The core purpose is front-loaded in the first words: 'Count characters.'

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?

Given no annotations, no output schema, and nine optional parameters, the description is insufficiently complete. It never specifies that a single `query` argument is the only effective one, nor what the count result is, so an agent cannot reliably invoke the tool.

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?

Because the schema covers each parameter in 100% of its text, the description is not required to repeat them. The description does link 'search query' to the conceptual input and says the query is discarded, but it does not explain why the other eight parameters exist or how to select among them.

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 and resource: 'Count characters in a search query.' This clearly distinguishes the tool from siblings like utf8-bytes (byte count) and hn-front-count (item count), and matches the tool name.

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 on when to use this tool versus alternatives, nor does it mention which of the nine schema properties is relevant. It ends with 'Query discarded' but never says 'provide the query parameter' or when to choose this over another length/shape-check tool.

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