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

Annotations already cover the safety profile (readOnly, idempotent, closed-world, non-destructive), so the bar is lower. The description adds real context: it reads from the user's saved Deckodex targets, and it discloses the behavioral difference between omitting set (per-set overview) and supplying set (rarity breakdown), which annotations cannot convey.

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, front-loaded with the core computation and cost before the optional-set behavior. The em-dash asides are slightly dense but each clause carries distinct meaning without redundant repetition of the name.

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 most of the work by describing return content (completeness percentage, cost to finish, per-set rarity breakdown) and default-resolution behavior. It is nearly complete, though it does not describe currency/price-source handling for the source parameter or output granularity beyond the set level.

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%, so baseline is 3; the description goes further by unpacking the mode enum (unique cards, playsets = 4 of each, master = every printing) and clarifying that default mode/source come from the user's saved Deckodex settings, plus what the optional set parameter adds.

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: computes how complete the user's collection is per set, with explicit mode variants (unique/playset/master) and a cost-to-finish output. It clearly differentiates from a simple collection listing by the set-level, completion-and-cost framing, though it does not name siblings like my_collection or my_collection_value.

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 only implied: the reader infers the tool is for per-set completion tracking, and 'With set: that set's rarity breakdown' hints that supplying a set changes behavior. There is no explicit when-to-use, when-not, or alternative routing versus my_collection or my_collection_value.

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