part_details

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

With no annotations, the description carries the full burden. It discloses a key behavioral trait: distributor part numbers only resolve at the issuing distributor, and results will normally come from that source alone. This is genuinely non-obvious and valuable. It does not mention auth, rate limits, or error handling, but for a lookup tool with an output schema, this covers the main gotcha.

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 sentences, each earning its place. The first states the core purpose; the second delivers a critical behavioral caveat. No filler, no repetition, and the purpose is front-loaded. This is an efficient, well-structured description.

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?

Given the tool's low complexity (2 parameters, 1 optional), the existence of an output schema, and the key distributor caveat being addressed, the description is functionally complete. It lacks only more explicit usage routing, which is covered under usage guidelines, but overall nothing essential is missing for safe invocation.

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%, and the schema already includes detailed descriptions for both parameters, including concrete examples for part_number (e.g., '296-1234-ND' for DigiKey) and the meaning of sources. The description adds no additional parameter-specific meaning beyond what the schema provides, so the baseline of 3 is appropriate.

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 clearly states the action ('look up one part by part number'), the resource ('part'), and the scope ('full specifications and pricing'). It distinguishes from sibling tools: search_parts is for searching, source_status is for status, and clear_cache is for cache management. No ambiguity.

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 hints at when to use this tool (when you have a specific part number) versus searching, but it does not explicitly name alternatives or exclusion conditions. The distributor-resolution note gives behavioral context but not direct routing. Sibling differentiation is implied rather than stated.

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