Chat messages

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

Adds context beyond annotations: specifies read-only (confirms readOnlyHint=true), does not mark chat as read, and describes pagination and sorting. No contradiction with 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?

Three concise sentences front-loading key information—purpose, read-only note, prerequisites, pagination, and related tool. No superfluous content.

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?

Despite no output schema, description covers return content and sorting, and provides links to related tools. Completely informs agent selection and invocation.

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 coverage is 100% with descriptions; description adds value by explaining chat_id origin, pagination parameters, and default user_id.

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?

The description clearly states the tool returns messages of a specific chat, sorted newest to oldest, and lists content types (text, images, voice, links, date, author). It distinguishes from sibling tools like messenger_get_chats_v2 and messenger_chat_read.

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?

Explicitly notes read-only behavior, does not mark as read (suggests messenger_chat_read), requires chat_id from messenger_get_chats_v2, pagination via limit/offset, and directs to messenger_get_voice_files for voice downloads.

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