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

Annotations already declare the mutation is non-read-only, non-destructive, and non-idempotent. The description adds meaningful context beyond that: it explains how different media types map to block types and explicitly states it does not publish or change existing delivery snapshots, plus implies optimistic concurrency via 'read the post revision first'.

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 tightly written sentences, front-loaded with the usage condition, followed by prerequisite, behavioral mapping, and scope boundary. No filler or redundancy.

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. Still, for a mutation tool with a close sibling (attach_media_to_draft), the description lacks explicit sibling differentiation and parameter detail, leaving some ambiguity about when to use this versus its counterpart.

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 gives partial cues: mediaId is a 'finalized owner mediaId', postId is a 'working post', and expectedRevision relates to reading the post revision first. But it omits format details, constraints, and what 'owner' entails, leaving significant gaps for an undocumented 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 (adding) and resource (finalized owner mediaId to a working post). However, it does not differentiate from the sibling attach_media_to_draft, leaving ambiguity about which attachment tool to use in a given context.

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?

Provides a clear when-to-use context ('adding a finalized owner mediaId to a working post') and a prerequisite ('Read the post revision first'), but offers no explicit alternatives, when-not-to-use conditions, or guidance on choosing between this and attach_media_to_draft.

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