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

With no annotations, the description carries the full burden and does disclose real behavior: results are compared spec by spec, confidence is defined (high = every rule verified, medium = some spec unreadable), and categories without rules degrade to 'unverified similar parts' that are clearly marked. It does not state that the call is read-only or whether results are ranked, but the verification/confidence semantics are the substantive part and they are covered.

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 dense sentences, front-loaded with what the tool returns before explaining confidence levels and the no-rules fallback. No filler, though the parenthetical spec list is slightly list-heavy for the value it adds.

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 7-parameter tool, completeness largely rests on the schema (86% described) and the output schema, both present. The description fills the remaining conceptual gap — how 'compatible' is determined and what confidence means — leaving only minor gaps such as result ordering and the cost/latency of the verification.

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 86%, so the schema already documents part, qty, manufacturer, same_package, no_assembly_fee, and project_id. The description's spec list (voltage, current, tolerance, dielectric) describes the matching engine, not any parameter, so it adds little parameter meaning beyond what is already structured. Baseline 3 applies.

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 — compatible replacements for a part, validated spec by spec (value, polarity, voltage, current, tolerance, dielectric). This is meaningfully distinct from the sibling find_parts (search) and get_part (lookup), though it never explicitly names those siblings as the alternative.

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?

Usage is implied: use it when you need to replace an existing part rather than find a new one. There is no explicit when-to-use/when-not framing, no mention of prerequisites (e.g., unresolved MPN, manufacturer disambiguation), and no routing to find_parts or check_bom.

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