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

With no annotations available, the description carries the behavioral burden. It does disclose that the query is discarded, which is a meaningful privacy-related behavioral trait. However, it never states what the output format is, whether anything is returned besides a count, or whether any side effects exist 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 very short and front-loaded, with no filler. However, it is under-specified rather than efficiently complete, and the second sentence 'Query discarded' adds behavior but leaves unanswered questions about the return value and parameter mapping.

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 seven input parameters, no output schema, and no annotations, the description is too incomplete. An agent cannot determine which parameter to pass, what the tool returns, or how to interpret the result. The tool's behavior is only partially explained.

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?

The description refers to a 'search query,' but none of the seven schema properties is named or described as a query. The parameter descriptions are present but do not connect to the core functionality. The description therefore fails to clarify which parameter an agent should provide or how the schema properties map to 'a search query.'

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 gives a specific action and resource: 'Count characters in a search query.' This is clear on its face and is distinguishable from siblings like memory-key-count or hn-front-count. However, it does not explicitly contrast itself with any sibling, and the term 'query' is not obviously represented in the input schema.

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, and no mention of restrictions or prerequisites. The sentence 'Query discarded' implies a non-persistent, low-risk operation, but that is the only contextual hint and it does not explain when this tool should be selected.

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