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

Annotations only cover the safety profile (readOnly=false, destructive=false, idempotent=false), so the description adds real value: a hard six-file cap, per-file format/10 MiB limits, an explicit 'Never publishes' guarantee, the returned display instructions, and error handling via nextAction. It stops short of explaining duplication behavior implied by idempotentHint=false.

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?

Front-loaded with the usage trigger and limits, and no sentence is pure filler. The back half is a run-on of abrupt imperatives ('Include the image... Inspect preview_post. On error follow nextAction...') that makes the ordering harder to follow.

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?

Given an output schema exists, the definition needn't explain return values, yet it still covers limits, the exact-placement alternative, preview verification, and error recovery. An agent has enough to call it correctly, though the sibling distinction remains unexplained.

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?

With 80% schema coverage the baseline is 3, but the description usefully consolidates the two input paths ('mediaFile1..mediaFile6 or mediaFiles') and the six-file total cap into one sentence. It largely reinforces rather than extends the schema text on those fields.

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 ('attach media' to a 'draft') and frames the core constraint ('while preserving draft text'). It does not, however, distinguish itself from the sibling 'attach_media', leaving the agent to infer which of the two to pick.

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?

Opens with an explicit trigger ('Use this when adding images while preserving draft text') and routes the exact-placement case to update_post_draft with richDocument and slot bindings. It gives a clear context but no exclusion relative to the similarly named attach_media sibling.

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