Validation message count

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

Annotations already declare readOnlyHint and openWorldHint. The description adds that the result is returned as text and explains the recheck behavior, implying potential caching of results without recheck. This exceeds basic annotation coverage without contradiction.

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 concise sentences deliver the purpose and the key conditional. No filler or redundant details.

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 counting tool with 2 parameters and no output schema, the description covers the return format (text), the recheck condition, and the document parameter via schema. The annotations handle safety and external behavior, so the tool is adequately specified.

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 input schema provides 100% coverage of both parameters (doc and recheck). The description repeats the recheck semantics already in the schema and adds no new parameter-specific meaning.

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 the function: returning the number of error messages in the accounting file as text. It distinguishes from siblings like banana_messages (which likely lists messages) and banana_table_rowcount by specifying the resource 'accounting file' and the count format.

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 provides a clear conditional usage for the recheck parameter ('Set recheck=true to force a fresh...'), indicating when to trigger a recheck. However, it does not explicitly contrast with alternative tools (e.g., banana_messages) or mention when not to use this tool.

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