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

With no annotations, the description carries the burden. It does disclose that the query is discarded, which is a meaningful no-retention/no-persistence trait. But it does not state whether the call has side effects, rate limits, or what the return value is; for a simple read-only counter that is arguably sufficient, but not fully transparent.

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?

Two short sentences, front-loaded with the purpose and closed with the discard behavior. Every word earns its place; no redundancy or filler.

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 has 9 optional parameters and no output schema, but the description only addresses the 'query' parameter and the return format is left implicit. An agent cannot tell why the other eight fields exist or whether they are valid inputs, making the definition incomplete for a tool with this schema complexity.

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 already documents each parameter. The description adds no new meaning for 'query' and mentions nothing about the eight other parameters; it is consistent with the schema's 'query' description but does not compensate for the broader schema.

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 uses a specific verb ('Count') and object ('characters in a search query'), making the tool's function immediately clear. It also distinguishes this from sibling count tools by targeting search queries specifically. However, it doesn't name the query parameter or acknowledge the other schema fields, so a little ambiguity remains.

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 when-to-use/when-not-to-use guidance, no prerequisites, and no mention of alternatives. The reader must infer from the name and purpose that this is for measuring query length. No exclusions or edge-case guidance is provided.

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