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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds real behavioral value: each folder carries creative_count, empty results relate to coverage.empty_reason, and a NOTE warns that updated_at is 'row last touched' not 'content changed', advising self-diffing. This is meaningful 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, followed by scoping, behavioral caveats, and a parameter recap with example. The NOTE and REQUIRED/OPTIONAL/EXAMPLE blocks are dense but each earns its place; slightly verbose but not wasteful.

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 still conveys return-relevant fields (creative_count, coverage.empty_reason). For a read-only, zero-required-param list tool this is nearly complete; only connection_context is left unaddressed.

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 carry the burden. It documents parent_id well (str, UUID of parent folder, omit for top-level) but leaves connection_context entirely unexplained, so it only partially compensates for the coverage gap.

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 (List) and resource (creative folders) with scope (authenticated tenant, optionally parent_id-scoped). It distinguishes itself from the sibling creatives_list by clarifying that root creatives_list still returns READY_LOCAL files with folder_id=null.

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?

Gives clear usage context: omit parent_id for top-level, and explicitly instructs the agent to inspect coverage.empty_reason before telling the operator the library is empty. It also warns that zero folders does not mean an empty library. It lacks an explicit 'use X instead of Y' routing statement, keeping it from a 5.

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