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

The description goes well beyond the annotations by disclosing the billing cost (300 micro-dollar service credits per successful call), the billable distinction for new requestIds, the preparation prerequisite, and the 'recovery' reuse semantics. It also adds technical behavior like preserving UTF-16 surrogate pairs, which is not present in the annotations or schema.

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 compact and front-loaded: the core capability comes first, followed by billing and prerequisite information. Every sentence carries operational value, and the recovery note is especially important for correct repeated use.

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 paid tool with prerequisites and an output schema, the description is complete: it covers preparation, authentication, credits, billing behavior, idempotent recovery, and output characteristics. Nothing essential is missing for an agent to invoke and interpret this tool correctly.

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 coverage is 67%, with requestId and maxPriceMicroUsd already described. The description adds meaningful context for the chunking behavior, such as 'overlapping,' 'at most 200,' 'offsets,' and UTF-16 safety, which helps interpret input.overlap and input.text, though it does not explicitly explain maxChars semantics beyond schema constraints.

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 opens with a specific verb and resource: 'Split text into at most 200 overlapping chunks with offsets and intact UTF-16 surrogate pairs.' This precisely defines the tool's function and its key output characteristics, and the chunking behavior clearly distinguishes it from the unrelated 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?

The description clearly tells the agent to call agent_utilities_prepare first, requires existing credits and a private Authorization header, and explains the recovery pattern with reused prepared arguments. It provides strong contextual usage guidance, though it does not explicitly mention when not to use this tool or compare it to alternative tools.

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