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

Annotations already establish read-only, idempotent, closed-world behavior, so the description does not need to repeat safety traits. It adds useful context beyond annotations: the catalog is curated, researched and sourced, each entry is tied to a founding event, and the actual chart data is elsewhere. It does not describe result ordering or pagination, which keeps it from 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?

The description is two tight sentences with no waste. The first sentence front-loads the catalog contents and scope, and the second sentence cleanly establishes the boundary with the Mundane suite.

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 simple read-only catalog lookup with one optional documented parameter and no output schema, the description gives enough context to call it correctly. It explains what the library contains, what each entry represents, and where chart details live, leaving no significant gap for the agent.

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 the single search parameter is already documented as a name filter with an example. The description does not add syntax, matching behavior, or other semantics beyond the schema, so the baseline of 3 is appropriate.

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 states a precise resource and scope: the national charts (198) and empire charts (19) that Naelos holds, including what each entry contains. It also distinguishes this catalog from the actual chart data by saying the charts themselves are in Naelos's Mundane suite. An agent can tell this is a holdings/library lookup rather than a chart-calculation tool.

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?

The description gives clear usage context: use this to see which researched and sourced charts Naelos holds and what founding event each is cast for, while the charts themselves belong to the Mundane suite. It does not explicitly name a sibling tool as an alternative or state exclusions, but the boundary is clear enough for selection.

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