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

The description adds one behavioral note: 'Calls record usage and query metadata within POKEKA,' which discloses a side effect (usage recording) not present in annotations (readOnlyHint: false). This is useful, but it does not address other behaviors like rate limits, authentication, or optionality of 'when available.'

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 fluff. The first sentence front-loads the core purpose and data breakdown; the second adds a relevant side-effect note. Efficient and well-ordered.

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 single-parameter query tool with an output schema, the description covers the essential payload (grades, gem rate, scarcity) and notes the 'when available' caveat. It does not explain pagination or error cases, but the output schema handles structure and the annotations handle safety.

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 card_id parameter already carries a clear description ('from search_card / slang_lookup'). The tool description adds nothing beyond saying 'one card,' so it does not improve on the schema's parameter explanation.

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 resource ('one card') and a specific data type ('graded population'), enumerating exact metrics (PSA population by grade, CCIC population, gem rate, scarcity tier). This clearly differentiates it from siblings like card_price or recent_sales, which are about prices/sales rather than population counts.

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 when to use it ('Graded population for one card') but does not explicitly state when not to use it or name alternative tools. It could guide the agent by saying 'for population data, not prices/history,' but it leaves that to the sibling list.

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