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

No annotations are present, and the description adds one transparency detail: 'Query discarded.' It does not mention auth, rate limits, or any other side effects, but for a read-only character count the discard note is meaningful.

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 extremely concise at two short sentences. It front-loads the action and states the key data-handling fact without padding.

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?

For a simple character-count tool, the missing output schema is not a major issue, but the description leaves important context unclear: whether all characters count equally (whitespace, Unicode, etc.) and why the input schema includes many apparently irrelevant optional fields.

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 the schema carries most parameter meaning. The description adds little beyond the schema's existing 'Search text; discarded after the length check' note, and it does not clarify why several unrelated optional parameters exist.

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 verb and resource: 'Count characters in a search query.' It does not explicitly distinguish itself from sibling tools, but the resource is specific enough that an agent can infer basic intent.

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 given about when to use this tool versus alternatives. There are no conditions, prerequisites, or examples, leaving the agent to infer suitability from the name and one-line description.

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