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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered. The description adds genuinely new behavioral context by disclosing entitlement gating ('Deckodex Pro adds longer ranges (3M, 6M, 1Y, ALL)'), which tells an agent that certain range values depend on the user's plan.

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?

Front-loaded with what the tool returns, then the Pro extras. Two sentences with no filler, though the second sentence is a dense laundry list of Pro features that reads more like marketing than call-relevant detail.

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 no output schema, the description does the work of telling the agent what comes back (current value, change over windows, Pro breakdowns like value by set and top holdings). It is close to complete for a zero-required-param read tool, missing only explicit guidance on fallback behavior when Pro is absent.

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 67% and all three params are enums. The description adds meaning for `range` by tying 3M/6M/1Y/ALL to Pro, and `mode`'s 'recorded' is already explained in the schema. Beyond that it does not add syntax or default guidance, so the 3 baseline fits.

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?

States a specific verb+resource ('what the signed-in user's Gundam collection is worth') plus the temporal dimension (7 days, month, longer ranges). It is clearly distinguishable from siblings like my_collection and my_set_completion, though it never names them or contrasts itself explicitly.

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?

Usage is implied rather than stated: the mention of 'now and how it changed' plus Pro ranges signals valuation-over-time, but there is no explicit when-to-use-this-vs-my_collection guidance and no mention of prerequisites for the Pro-gated ranges.

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