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

readOnlyHint=true already tells the agent this is a safe read with no side effects, so the bar is lower. The description adds useful scope context (three marketplace types, all three searched when marketplace is omitted), but discloses nothing about result volume, pagination limits, or rate behavior.

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 dense sentence, front-loaded with the verb and resource and then the scope and filter axes. No filler, though the filter list slightly duplicates what the schema enumerates.

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, full annotation coverage, and 100% parameter documentation, the description only needs to orient the agent, which it does. Missing only explicit sibling routing for a tool with several closely related fanaticscollect_* companions.

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% across all 22 parameters, so the schema already carries the semantics of each filter. The description only restates the filter categories (free-text, category, grading service, ranges, status, sort) at a higher level, adding no syntax or edge-case detail beyond the schema.

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 (Search) and resource (Fanatics Collect's full marketplace) and enumerates the three covered marketplaces and the filter dimensions, which lets an agent tell it apart from fanaticscollect_listing or fanaticscollect_auctions. It stops short of naming a sibling directly, so it is clear but not maximally differentiating.

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: 'full marketplace' suggests a broad browse entry point, but there is no explicit when-to-use/when-not-to-use guidance or any statement pointing to fanaticscollect_listing for detail or fanaticscollect_sold_items for sold data. Nothing is misleading, but the agent must infer the routing.

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