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

Annotations already declare read-only, idempotent, non-destructive behavior, so the description does not need to restate those. It adds genuinely useful behavioral context beyond the annotations: Pro-only longer ranges, recorded value history, value by set, top holdings, and gainers/losers. It does not describe output format, but the annotations carry the safety profile.

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?

Two sentences with no filler. The core purpose is front-loaded, and the second sentence efficiently enumerates Pro capabilities without restating schema fields or annotations.

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 read-only tool with three optional, well-schemaed parameters and no output schema, the description gives enough high-level context about what values are returned and which features require Pro. It does not detail the exact response shape, but the annotations and schema cover the operational essentials.

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?

With 67% schema description coverage and detailed mode/source descriptions already present, the baseline is near 3. The description adds value by clarifying that 3M/6M/1Y/ALL ranges are Pro additions and by mentioning the 'recorded value history' concept tied to the recorded mode. Source semantics are not enriched, but the schema already covers them.

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 clearly identifies the resource (signed-in user's Gundam collection) and the purpose (current worth and change over 7 days/month). It is specific enough to distinguish this from sibling tools like my_collection or price_list, though it uses a noun-phrase framing rather than an explicit action verb.

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 implies usage for collection valuation and change-over-time questions, and it notes that longer ranges are Pro-only. However, it does not explicitly say when to prefer this tool over siblings such as best_buys, market_movers, or my_collection, nor does it mention when not to use it.

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