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

With readOnlyHint and openWorldHint already declared, the description still adds real behavioral context: the aggregation semantics (every seller's copy of a card+grade collapses into one row) and what each row contains (identity, image, price, a chaining handle). It does not discuss pagination or rate limits, but the aggregation disclosure is substantive value beyond the annotations.

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?

Purpose is front-loaded and the sibling/chaining relationships follow logically. The two sentences are dense but each clause carries information; slightly run-on, but nothing is wasted.

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 7-param read tool with an output schema present, the description covers the key semantics an agent needs: result granularity, the category/query optionality, and the handoff to comc_listing. Return-value explanation is appropriately delegated to the output schema.

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%, so the baseline is 3. The description restates that category takes a comc_categories slug (already in the schema) and clarifies the query/category optionality, adding only marginal meaning beyond what the schema already documents.

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 ('Search or browse COMC's live consignment marketplace for graded and ungraded trading cards') and goes further to explain the result granularity (distinct card+grade rows). It clearly distinguishes itself from comc_listing, which it names as the per-seller drill-down target.

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?

Explicitly routes the agent: category must be a slug from comc_categories, and comc_listing is the tool to chain into for per-seller breakdown. It also notes both category and query are optional with a defined fallback ('omitting both searches everything'), though it stops short of stating when not to use this tool.

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