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

No annotations are present, so the description carries the full burden of behavioral disclosure. It mentions 'Query discarded' but does not explain that the other parameters are also discarded after shape checks, nor does it clarify that the tool accepts many parameters but only uses the query. It also does not disclose read-only nature or side effects, leaving significant behavioral ambiguity.

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 concise at two sentences, with the core action front-loaded. There is no redundant content. However, given the tool's complexity (9 parameters), it might be overly terse, but conciseness itself is good.

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?

With 9 parameters, no output schema, and no annotations, the description is inadequate. It does not explain the role of the 8 non-query parameters, nor does it describe the return value or behavior for missing inputs. An agent would struggle to understand how to use this tool correctly beyond the query length check.

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 input schema provides 100% coverage with descriptions for all 9 parameters. The tool description adds no additional parameter semantics beyond what the schema already documents. Per the calibration baseline for high schema coverage, a score of 3 is appropriate since the description does not compensate or enhance parameter understanding.

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 action: 'Count characters in a search query.' This clearly identifies the primary function and resource, distinguishing it from sibling tools that check shape or validity. However, the presence of 8 other parameters in the schema is unexplained, which could confuse an agent 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?

No guidance is provided on when to use this tool versus alternatives. It does not mention any conditions, exclusions, or alternative tools. The description only states what it does, leaving the agent to infer appropriate usage without explicit direction.

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