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

Annotations already cover read-only/idempotent/non-destructive, so the description is free to add the parts that matter: the `properties` block is copy-ready for a node of that `type`, `provenance` is per supplied key, and `filledFromDefaults` lists keys the library did NOT supply (registry defaults, not datasheet figures). That trust caveat is exactly the kind of behavioral context annotations cannot carry.

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 purpose, and nearly every clause earns its place (the filledFromDefaults warning, the miss semantics, the schema-confirmation step). It is, however, a single dense em-dash-heavy block that could be broken up for faster scanning.

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 the full burden of describing the return shape — `properties`, `provenance`, `filledFromDefaults`, and the descriptive keys — and it does so fully, including how to use the returned `properties`. Nothing an agent needs to call or interpret this correctly is missing.

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 the baseline is 3, but the description adds meaning beyond the schema strings: `mpn` is an exact lookup, `type` is a filter whose result comes back as a `types` list. This clarifies how each parameter affects the response rather than merely restating the schema descriptions.

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 ('Retrieve parametric simulation models from the Electronics Architect curated part library') and immediately bounds it against what it is not ('NOT pricing or stock'). An agent can distinguish it from siblings like get_design_schema (which it explicitly defers to) and from any pricing/stock tool 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?

Gives explicit routing: filter by `type` or look up an exact `mpn`, confirm the `type` with get_design_schema first, and tells the agent what a miss means ('enter the datasheet values by hand', not 'the part does not exist'). It also names the when-not case (pricing, stock, distributor search unavailable here).

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