Add line items to a job

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

Annotations declare the safety profile (readOnly=false, destructive=false, idempotent=false), so the description needn't restate mutability. It adds real behavioral context beyond that: the existing-job precondition, the unitPrice-overrides-catalog rule, and the name-based catalog-matching fallback when price is omitted. It does not mention that repeated calls are non-idempotent and will add duplicate lines, a notable gap for a write tool with idempotentHint=false.

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 tightly written sentences, front-loaded with the action and scope, then the alternative routing, then the price-handling rule. No filler or repetition of the title.

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?

Covers the action, routing, and the key pricing ambiguity for a moderately simple 3-parameter tool whose schema is fully documented. It stops short of describing what the call returns or the non-idempotent duplicate risk, which are the only real omissions.

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 100%, so the baseline is 3, but the description adds the precedence behavior between unitPrice and catalog name matching that goes slightly beyond the field-level text. It does not explain how jobId and customerName interact for identifying the target job, though the schema covers both.

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 and resource ('Add billable line items to an EXISTING job') and immediately scopes it against the sibling create_job path. The 'EXISTING' emphasis plus the sibling reference lets an agent distinguish it from create_job without opening either schema.

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?

Gives an explicit when-to-use trigger with a concrete user utterance example ('add a $50 cable management charge to the Smith job') and names the alternative tool plus its condition for new jobs. Both the positive and negative cases are covered.

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