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

Annotations already establish readOnly/idempotent/non-destructive behavior, so the safety profile is covered. The description adds genuinely useful scope context: the output is an economic model (per-outcome net profit, expected value, break-even gem rate) and it explicitly disclaims condition assessment, which prevents a false expectation. It does not mention fee-tier behavior beyond what the schema says, keeping 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 trigger is front-loaded in the first clause, followed by the output inventory and the prerequisite/disclaimer. The long enumeration of return values partially overlaps the output schema, but each clause is informative and nothing is padded.

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 need not enumerate return values in detail; it instead supplies the missing decision context (when to call it, what card id source is needed, what it does not do). Combined with rich annotations and 100% schema coverage, an agent has everything required to select and invoke it correctly.

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 description coverage is 100% and both parameters are documented there, including the grading_fee default and comparison tiers. The description adds no syntax or format detail beyond restating that a card id from search_cards is required, so the schema is doing the heavy lifting.

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 specific decision verb ('whether a card is worth grading') plus the concrete artifact returned (raw vs PSA 9 vs PSA 10 prices, gem premium, break-even rate, verdict). It is clearly distinguishable from sibling list/price tools like get_card_prices and best_cards_to_grade because it is scoped to a single card's grading economics.

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 an explicit trigger ('when the user asks whether a card is worth grading, submitting to PSA/CGC/BGS/SGC/TAG, or what a PSA 10 adds') and an explicit exclusion ('does not assess the condition of the user's copy'), plus a prerequisite (card id from search_cards). It stops short of routing the agent between this and the bulk sibling best_cards_to_grade, so it is not a full 5.

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