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

With no annotations at all, the description carries the full burden, and it does disclose the two things an agent most needs: a per-call cost of $0.01 USDC on Base (eip155:8453) and the exact payment channel in params._meta["x402/payment"], plus the underlying HTTP endpoint. What it omits is any behavioral disclosure about the result itself (format of the explanation, handling of invalid expressions, whether count defaults).

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?

Three short sentences with purpose front-loaded, followed by price/payment and transport. Nothing is padded, though the raw HTTP endpoint is of marginal value to an MCP caller already invoking the tool by name.

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 3-parameter tool with zero annotation coverage, no output schema, and 0% schema description coverage, the description covers purpose and payment mechanics but leaves parameters and return shape unexplained. It is adequate to know what the tool is for and how to pay, but not quite adequate to call it correctly on the first try.

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 0%, so the description must compensate and largely does not. It implies cron (the expression being explained) and loosely implies count (the number of next run times), but tz is never mentioned and no formats, defaults, or valid ranges are given. Notably it also does not flag that all three parameters are optional per the schema.

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 gives a specific verb-plus-resource: a plain-English explanation of a cron expression plus its next run times. That is clearly different in kind from a bare parse/validate routine. It does not, however, name the obvious sibling agentkit__cron or agentkit__cronbatch, so an agent cannot tell from the text alone which of the three to pick.

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?

There is no statement of when to use this rather than agentkit__cron or agentkit__cronbatch, and no exclusions. The only conditional context is the payment prerequisite (x402 in params._meta), which tells the agent how to pay but not when to choose this tool.

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