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

Annotations already cover the safety profile (readOnly, non-destructive, openWorld), and the description adds real value beyond them: newest-first ordering, the per-conversation fields returned, and the partial-failure behavior where unloadable accounts surface in an errors array with reasons such as missing message access.

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?

Two sentences, zero filler, with the resource and ordering front-loaded and the return/error behavior second. Every clause carries information.

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?

With no output schema, the description usefully enumerates the returned fields (id, accountId, participantId, last message) and the errors array. It is close to complete for a read-only list tool, though it omits pagination/limit behavior.

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 the schema already documents platform, accountId and workspace; the baseline is 3. The description only reinforces the platform values by naming the three supported networks, adding little for accountId or workspace.

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 ("List direct message conversations") plus ordering and the exact platform scope (Facebook Pages/Messenger, Instagram, X), which cleanly separates it from the sibling get_conversation_messages that fetches messages inside a conversation.

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?

Usage is only implied: an agent can infer this is the entry point before get_conversation_messages, but the description never states when to prefer it over alternatives or any prerequisite (e.g., needing a connected account). No exclusions or routing guidance are given.

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