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 covered. The description adds the 50-item batch ceiling and the intended workflow position, but says nothing about cursor behavior for pagination, partial failures, or connection_context validation. Useful context, but not rich beyond 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?

A single front-loaded sentence with no wasted words; the count constraint and the workflow hint both earn their place. It is slightly telegraphic ('after listing the index' could be clearer) but never padded.

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 not be described, and annotations cover the safety profile. The batch cap and ordering guidance complete the core picture for a read-only batch fetch; only cursor/pagination semantics and connection_context usage remain 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 carries the full burden, yet it only loosely gestures at media_refs ('selected ... previews') and the maxItems=50 ceiling. The cursor and connection_context parameters, including the mctx_v1_ token format, are left entirely unexplained by 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?

States a specific verb+resource ('Fetch ... account media previews in a batch'), includes the batch size constraint, and distinguishes itself from the single-item sibling by naming the anti-pattern it replaces ('avoid serial item probes'). An agent can separate it from account_media_get and account_media_list without opening any schema.

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 sequencing ('after listing the index') and an explicit when-not ('avoid serial item probes'), which routes the agent away from repeated account_media_get calls. It stops short of naming the sibling tool explicitly or stating prerequisites such as the media_refs format required.

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