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

The description discloses that the query is 'discarded after the length check,' which is a useful side-effect note. However, it does not describe the return value, output format, or any potential edge cases, and there are no annotations to fill the gap.

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 concise, using only two short sentences. It is front-loaded with the core purpose and contains no extraneous information.

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's nine optional parameters, the description is too sparse. It does not specify the expected return value, clarify that only 'query' is the intended input, or mention how the other parameters relate to the tool. Important operational context is missing.

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 schema has 100% description coverage, so each parameter is individually described. However, the description itself adds no extra meaning beyond the schema, and many parameters appear unrelated to the stated purpose, creating potential confusion about which parameter should be supplied.

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 explicitly states the tool's purpose: 'Count characters in a search query.' The verb 'count' and resource 'search query' are clear and specific. No sibling tool has a similar function, so it is well differentiated.

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 explicit guidance on when to use this tool versus alternatives. It does not mention any conditions, exclusions, or relationships to sibling tools, leaving usage context entirely implicit.

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