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

With no annotations available, the description carries the transparency burden. It adds one genuine behavioral detail—'Query discarded'—which indicates the operation has no lasting side effect on the input. It does not fully describe side effects for the other parameters or what the actual return value shape is, so it is not very complete but does provide useful evidence.

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 only two short sentences and avoids all fluff. It fronts the main purpose and then adds a valuable behavioral note. There is no redundant or filler content, making it highly efficient.

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?

The tool is simple and the description captures its core behavior, but with 9 params and no required fields, the description does not explicitly point the agent to which parameter to populate. It also omits the return value format, and the many distractor params in schema could confuse a caller without a clear 'use the query parameter only' message. Still, schema descriptions fill some of these gaps, so it is minimally complete.

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 this is the baseline for a description that adds nothing extra. The description references 'search query' but does not explicitly map that to the `query` parameter, nor does it clarify that the other eight params are ignored. The schema itself covers param details, so the description adds limited new semantic value.

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 the tool's function with a specific verb and resource: 'Count characters in a search query.' It is unambiguous and distinguishes this from sibling length/count tools by its focus on a search query. The second sentence adds a clean behavioral note without muddying the purpose.

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 on when to use this tool versus alternatives, such as when a search-query length is needed or when no counting should be done. It does not mention any alternate tools or exclusion criteria. The instruction is fully absent beyond the purpose itself.

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