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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds genuine value beyond that: it states what is returned (complete actuators plus composed joints with torque/speed math, price and mass totals, quote-needed flags, lead times, origin), and importantly discloses the limitation that checks the catalog cannot make are reported as 'not checked'.

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, front-loaded with the verb and the input targets before moving to output detail. Dense but every clause carries information; only the output clause runs long and could be broken up for readability.

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?

There is no output schema, so the description must explain returns — and it does so thoroughly (assemblies, breakdowns, math, pricing, quotes, lead times, provenance, unchecked items). Combined with readOnly annotations, an agent has enough to call it correctly; only the 'limit' parameter's effect on result count is left unaddressed.

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%, with descriptions already present on speed_rpm, voltage_v, max_mass_g and peak_torque_nm. The description restates those same dimensions in prose and does not clarify units, defaults, or the unmentioned 'limit' parameter (result count, capped at 20), so it adds little beyond the schema baseline.

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 opens with a specific verb+resource ('Plan a complete robot joint') and immediately enumerates what it plans from (peak torque, output speed, bus voltage, mass budget, quantity), which no sibling tool does. It is clearly distinguishable from search_parts, compare_parts or match_requirements.

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 by the framing 'from targets' and by the choice of target-oriented inputs, so an agent can infer this is the sizing/design entry point. However, there is no explicit when-to-use or when-not guidance, and no named alternative such as search_parts or match_requirements for agents who only need to look up existing parts.

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