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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds that the returned links are 'signed' (implying time-limited URLs), which is mild behavioral context, but says nothing about auth requirements, error behavior, or link expiry.

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 front-loaded clause with zero filler: verb, resource, key, then the return payload. Nothing to trim and nothing buried.

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?

An output schema exists, so return values need no elaboration, and annotations cover the safety profile. The description is nearly complete for a simple read tool; the only real gaps are the unexplained connection_context parameter and the absence of routing guidance to sibling retrieval tools.

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 parameter meaning. It does clarify that selection_key identifies the single creative to fetch, which is genuinely useful, but connection_context is left entirely unexplained in both schema and description.

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?

Specific verb (Get) + resource (one owned creative) + selector (selection_key), and it states what comes back (details, signed download and thumbnail links). It implicitly distinguishes itself from creatives_get_batch and creatives_list via 'one' and 'owned', but never names those siblings to route the agent.

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: you fetch a single creative when you already hold a selection_key. There is no explicit when-to-use, when-not-to-use, or comparison against creatives_get_batch, creatives_list, or creatives_pick, all of which are plausible alternatives in this namespace.

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