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

The annotations already declare this a read-only, idempotent, closed-world, non-destructive lookup, so the safety profile is fully covered. The description adds genuine context beyond that: the caesar-safe set is curated to import cleanly into CAESAR II, and `component` narrows rather than filters-out, implying a grouped registry structure. It stops short of noting size, pagination, or whether the full vocabulary is always returned.

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?

It is compact — two sentences — and the scope behavior is front-loaded before the narrowing parameter is mentioned. The first sentence is heavily packed with parentheticals ('component prefixes, end-condition suffixes, fitting and support keys'), which slows parsing slightly, but no sentence is wasted.

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 an output schema present the description needn't explain return values, and annotations cover safety, so the remaining burden is scope semantics — which are handled. The only soft spot is that it doesn't indicate how large the returned vocabulary is or whether `component` is required to get a manageable response, which matters for an enumeration-style tool.

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% and both parameters are already documented, so the baseline would be 3. The description goes further by giving concrete component group examples ('valve_prefix', 'safe_substitutions') that illustrate the naming convention and granularity beyond the schema's vague 'Optional group name within the scope', which meaningfully reduces guesswork.

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 names a specific verb ("Return") and two concrete resources: the Isogen-style SKEY vocabulary (prefixes, suffixes, fitting/support keys) and the PCF record set with substitutions. The scope enum splits the tool's two behaviors so an agent knows exactly which corpus it is retrieving, and this is clearly distinct from siblings like get_pipe_dimensions or lookup_value.

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?

It gives implicit but concrete selection guidance by explaining what each scope yields — 'isogen' for the SKEY registry, 'caesar-safe' for records that import cleanly into CAESAR II. That is enough to pick a mode, but there is no explicit when-to-use framing, no statement of when another tool (e.g. lookup_value) would be preferable, and no prerequisites such as required pipeline context.

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