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

Annotations already declare this is a non-read-only, non-idempotent, non-destructive, closed-world mutation. The description adds genuinely new behavior: all-or-nothing semantics (if any file is missing, nothing is added and the missing one is reported) and append-after-existing-media ordering. It does not discuss retry safety despite idempotentHint=false, which keeps it below a 5.

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 in the first clause, and each subsequent sentence carries distinct information: ordering, append position, atomic failure, and reporting to the user. The final reporting sentence is slightly verbose but earns its place given there is no output schema.

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 2-parameter mutation with no output schema, the description covers prerequisites, ordering, atomicity, and what to report back (count, order, cover file). The remaining gap is that the upstream preparation tool is referred to only as 'the preparation' rather than by name or ID-passing mechanics.

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%, so both parameters are already documented in the schema, which sets the baseline at 3. The description reinforces the ordering requirement for 'uploads' and the post-scoping for 'id' but adds no format or syntax 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 and resource — finishing the addition of media files to a post on the content calendar — and clarifies it is the terminal step after preparation commands have run. It implicitly separates itself from prepare-post-media-upload but never names that sibling explicitly, so the pairing is inferred rather than stated.

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 a clear precondition: call only after every command from the preparation has run, and send uploads in the same order. It stops short of explicit when-not-to-use guidance or naming the alternative tool, but the sequencing context is strong enough for correct invocation.

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