Validate a schedule

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

Goes beyond the read-only/idempotent annotations by disclosing conditional behavior: DST checks only run when tz is supplied, and Jenkins-style H slots only resolve when seed is given. The response contents are partly restated from the output schema, which lowers the added value somewhat.

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?

Front-loads the core action and result bundle, then appends dialect and parameter notes. The dialect enumeration (L, L-n, nW, LW, Ln, d#n) is dense and long but earns its place by telling the agent which syntax is accepted; the single-sentence output list is slightly heavy.

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 read-only, idempotent validator with an output schema, the description supplies everything an agent needs to call it: the three inputs' roles, supported syntax, and which checks are conditional. The only missing piece is routing guidance against sibling tools.

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 0%, so the description carries the full burden: tz is defined as the IANA zone the job will run in that activates DST checks, and seed as the prospective job name used to resolve H slots. Only the required 'expression' parameter is left implicit, which is acceptable given the tool name.

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 specific verb+resource ('Check a cron expression before saving it as a job') and enumerates what the validation returns (valid flag, engine error, plain-English description, normalized form, warnings, first run). It does not explicitly differentiate from the overlapping sibling cron_explain_schedule, 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?

'Before saving it as a job' implies the pre-commit validation use case, which is a clear context cue. However, no alternative is named and no when-not guidance is given, even though cron_explain_schedule and cron_suggest_slot sit next to it and cover adjacent needs.

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