add_collection_item

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

No annotations are provided, so the description carries the full burden. It mentions the 'exact match' behavior but doesn't disclose what happens on duplicate card_id (does it merge quantities or error?), whether price_variant/condition_note are validated against known variants, or what the output schema returns. For a mutation tool writing to local storage with 9 parameters, this is a transparency gap.

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?

A single efficient sentence that delivers the core purpose. Concise and front-loaded with the primary action. However, given the tool's complexity (9 params, 0% schema coverage, mutation with dual write semantics), the brevity borders on under-specification rather than economy.

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?

An output schema exists, so return-value documentation is not needed from the description. However, this is a multi-parameter mutation tool with zero schema coverage and no annotations. The description offers only the 'exact match' distinction, which is valuable but insufficient for an agent to correctly invoke this tool across its 9 parameters with confidence about behaviors like duplicate handling, currency/price semantics, and variant validation.

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 0%, so the description must compensate. It doesn't mention any parameters at all. The description hints at 'exact card' semantics which relates to card_id, but provides zero guidance on language, quantity, price_variant, purchase_price, or their relationships. With 9 parameters including a nuanced price_variant vs purchase_price distinction, the description fails to add meaning.

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 states the verb (add), resource (exact card to local storage), and a distinguishing characteristic (without inferring variant or condition). This differentiates it from similar collection tools like set_prices or add_to_watchlist, though it doesn't explicitly name sibling alternatives. The key behavioral distinction — exact match vs inferred variant — is useful.

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 phrase 'without inferring variant or condition' implies this is for cases where the user knows an exact card, but it doesn't explicitly state when to use this vs update_collection_item, remove_collection_item, or list_collection. No when-not-to-use guidance is given. The implied usage is clear but lacks explicit alternatives.

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