Add estimate items

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

Annotations declare the safety profile (mutating, non-destructive, non-idempotent, open-world), and the description usefully adds that items are appended rather than replacing anything and that the server computes totals and returns both the saved items and the new estimate total. This is genuine value beyond the annotations; it doesn't cover permission prerequisites or behavior against a locked/sent estimate.

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 tight paragraphs, purpose first, then mechanics and return value. No filler, no restatement of the schema's defaults and enums that would waste tokens.

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 mutation with no output schema, the description covers purpose, insertion behavior, field meanings, ID provenance, and what comes back. The remaining gap is operational edge cases such as item limits, locked estimates, or partial-failure behavior, which an agent might want before calling.

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%, so the description has real work to do, and it does it: it enumerates the meaningful item fields, clarifies that unit_cost is the agent's cost in dollars while markup is applied server-side to produce totals, and ties cost_code_id and section_id to their source tools. The nested item object is the crux of the call and it is described accurately.

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 ('Adds priced line items to an existing estimate') and scopes it to existing estimates. An agent can distinguish it from siblings like add_invoice_items or add_change_order_items purely by the resource named, without opening any 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?

Explains the insertion point ('at the end of an estimate section (the first one unless section_id says otherwise)') and where prerequisite IDs come from (cost_code_id from list_cost_codes, estimate_id from list_estimates/create_estimate). It gives clear context but never names exclusions or alternatives, e.g. that update_estimate is the tool for editing existing items.

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