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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint=false. The description adds that results are deterministic and equates the tool to a specific POST endpoint, which is useful behavioral context, but it omits any return format or error behavior.

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 followed by the API equivalence. No filler, though the endpoint reference is of marginal value.

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 one-parameter deterministic measurement tool with strong safety annotations, this is minimally workable. However, without an output schema and with no description of what statistics are returned, the agent cannot know what to expect from the call.

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 single required 'text' parameter has 0% schema description coverage, and the description does not compensate by explaining constraints such as max length, encoding, or accepted format. It merely implies that the text to measure is passed in.

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?

States a verb ('measure') and resource ('text'), but 'deterministically' does not specify which statistics are computed (e.g., character count, word count). It does not distinguish from sibling countText, leaving the agent to infer scope from the name.

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?

Provides no guidance on when to select this tool over siblings like countText or exactCalc, nor any prerequisites or exclusions. The only context is the underlying API endpoint, which does not help tool selection.

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