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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the mutation profile is covered. The description adds genuinely useful behavior beyond that: existing files are preserved unless overwrite is true, and the ZIP must be Base64 up to roughly 18 MB. It does not describe error behavior on size overflow, but the added semantics are solid.

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 tight sentences with the core action front-loaded ('Unpack a ZIP into the project folder'), followed by path-preservation detail and the overwrite/size constraints. No filler, though the colon-list of payload types is slightly dense.

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 mutation tool with annotations covering the safety profile and no output schema, the description supplies the missing behavioral context: overwrite semantics, size limit, and path-preservation. Return value needn't be described. Only failure-mode handling is absent.

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 only 33% (only design_id documented), so the description must compensate. It does for two of three params: overwrite's effect on existing files and zip_base64's format and size ceiling (matching the 24000000 maxLength). design_id is left to the schema, which is fine.

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 ('Unpack a ZIP into the project folder') and enumerates the concrete payload it distributes: footprints into a .pretty library, 3D models, and a library table. An agent knows exactly what the tool does without opening the 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?

Usage is implied by the description (add files to an existing project) but no when-to-use or when-not guidance is given, and no sibling (e.g. import_kicad_project, create_design) is named as an alternative for the initial-import case. Adequate but leaves routing to inference.

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