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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does disclose one useful trait, 'Query discarded,' establishing a read-only, no-retention operation, which is genuine value beyond the name. However, it never states the return value (does it return the numeric length or a confirmation?), how counting treats empty or non-ASCII input, or error behavior, so the disclosure is only partial.

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 two short sentences with zero filler, and the core action is front-loaded before the behavioral note. It is efficient and every word earns its place, though the extreme brevity for a tool with nine parameters and no annotations verges on under-specification, which keeps it from a top score.

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 9-parameter tool with no annotations and no output schema, a two-sentence description is incomplete: it never explains why the tool accepts a URL, city, timezone, JSON text, and file path alongside the search text, nor what the call returns or how it relates to the sibling shape/check tools. An agent reading the description alone cannot reliably determine the input contract or the output, so the tool depends entirely on the schema descriptions to be usable.

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 each of the nine parameters already has a textual description (e.g., 'Search text; discarded after the length check'), which sets the baseline at 3. The tool description adds no parameter-level meaning beyond restating 'search query,' which maps directly to the already-documented query parameter. No compensation for a coverage gap is needed because none exists.

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 first sentence states a specific operation, 'Count characters in a search query,' with a clear verb and resource, and the tool name aligns with it. It doesn't explicitly differentiate from sibling count/shape tools such as memory-key-count or hn-front-count, and the 9-parameter schema (ref, url, city, feed, host, json, path, zone, query) muddies which input is the actual subject, so it stops short of a 5.

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 offers no guidance on when to invoke this tool rather than a sibling such as memory-key-count, hn-front-count, or the various shape/check tools. There is no mention of conditions, alternatives, or the fact that the schema accepts nine different domain-specific inputs, leaving the agent to infer the usage context entirely. A sentence like 'use when you need the character length of search text' would close this gap.

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