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

Annotations already declare it as a non-destructive, closed-world read. The description adds genuine side-effect context beyond them: passing design_id records the lookup in the design's dossier and scopes registered parts, and the fallback path to a custom component database is disclosed. It stops short of describing result shape or any limits, so not a 5.

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?

Front-loaded with the core action, then layered usage rules and fallbacks in a logical order. Each sentence carries practical information, though the closing sentence on design_id is dense enough that it could be tightened.

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?

With no output schema, the description carries return-value burden and does reasonably well by saying the search returns package-suffixed variants to prefer. A 3-param read tool with full schema coverage needs little more; only the absence of result-format/pagination detail keeps it from a 5.

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 baseline is 3. The description adds real meaning on top: query is a substring match, design_id ties the lookup to a design dossier, and library is implied as a restriction scope. It does not clarify maxLength/pattern constraints, but it exceeds 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?

States a specific verb+resource+scope: searching KiCad's standard symbol libraries by name substring. It also distinguishes itself from siblings by name (get_kicad_symbol, create_custom_symbol), so an agent can tell it apart without opening schemas.

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 trigger ('use this whenever you are not 100% sure the (library, name) pair exists') plus branching guidance: prefer package-suffixed results, fall back to get_kicad_symbol(library='custom'), then register with create_custom_symbol. This is a full when/when-not/alternatives routing.

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