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

The description concedes 'Query discarded', which discloses that no side effects persist and the input is not retained. This is a meaningful behavioral trait. However, without any annotations the description is the only source; it does not mention return format (e.g., integer), encoding, or any operational constraints (e.g., max length), which are not revealed elsewhere.

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 exactly two sentences and delivers its core purpose and the key behavioral trait (discarding the query) with zero fluff. Each sentence does something: it defines the operation and then clarifies the side effect. The length is proportionate to the tool's doria; no wasted words.

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 the tool has 9 parameters, all optional, no output schema, and no annotations, a two-line description is not enough to fully instruct an agent. The description does not clarify whether all parameters are legal inputs or if only 'query' is used, and it does not give the return format. There is no guidance on how to interpret non-query parameters. So while the primary purpose is clear, the tool context is incomplete.

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% for all 9 parameters, so the baseline is 3 as the schema already documents each parameter. The tool description adds no additional meaning about the parameters; it only notes that the query is discarded. For the 'query' parameter, the schema description is equally explicit about the length check. Thus the description provides no extra semantic layer.

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 ('Count characters') and a specific resource ('in a search query'), which aligns with the tool name. It does not explicitly name sibling comparisons, but the resource is distinct enough that an agent can separate it from the other shape/count tools. The small gap is that the description ignores the other eight parameters declared in the schema, creating mild ambiguity about the tool's actual scope.

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 guidance on when to use this tool versus alternatives, nor any exclusions or call context. It simply states what the tool does, leaving the agent to infer that it should be used when a search query length is needed. No sibling routing or conditional advice is given.

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