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

With no annotations, the description supplies an important behavioral fact: the query is discarded, so the tool does not retain input. It also implies a read-only counting operation. It does not mention errors or return shape, but for a simple local length check this is largely sufficient.

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 terse sentences with no filler, and the core action is front-loaded before the side-effect. Every sentence earns its place.

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?

Despite full schema coverage, the description leaves the tool's contract under-specified: there are 9 optional parameters, no explanation of which one is the 'search query' to count, no explicit return type, and no guidance on why parameters like url, city, feed, or path are present. An agent cannot confidently predict behavior when multiple fields are supplied.

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 baseline is 3; each parameter is described, including 'query' as search text discarded after the length check. The description adds no parameter-level meaning beyond pointing at 'a search query'.

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') and resource ('a search query'), plus a notable side-effect ('Query discarded'). It is not a bare restatement of the name because it adds the discard behavior, though it does not explicitly differentiate from similar length/count sibling tools.

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?

Usage is implied: the agent can infer to use this when it needs the length of a search query. There is no explicit when-not/alternative guidance, which is a gap given the many sibling shape/check tools.

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