Get several media items at once

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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive behavior. The description adds valuable beyond-annotation context: the 50-item cap, the app-only media scope, and the partial-failure behavior where unreadable IDs appear in 'failed' instead of failing the whole call.

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?

Three tight sentences, each earning its place: the core capability, the preferred-use and scope guidance, and the failure behavior. The most important information is front-loaded and there is no redundant filler.

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 read-only batch retrieval tool with rich annotations, complete coverage of parameters in schema, and clear behavioral notes, the description leaves no material gap. It explains quota implications, scope, alternatives, and partial-failure semantics without needing an 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 coverage is 100%, so the baseline is 3. The description adds meaning by clarifying that media_item_ids are batched, limited to 50, and that individual failures are handled gracefully via a 'failed' field. This enriches the parameter's practical semantics 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?

The description uses a specific verb ('Fetch'), states the resource ('media items by id'), and gives a clear bound ('up to 50 ... in one call'). It also distinguishes itself from the singular get_media_item and from start_pick_session, making the tool's unique role unmistakable.

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?

The description explicitly says to prefer this over repeated get_media_item calls and explains why. It also provides the exclusion condition: for anything beyond app-uploaded media, use start_pick_session. This is direct, actionable routing guidance.

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