Mark chat as read

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

The description adds important behavioral details: 'Sends NOTHING to the other party... does not modify or delete any message'. However, it contradicts the annotations by claiming idempotency ('Idempotent: calling it again... is safe') while idempotentHint=false. This contradiction reduces reliability.

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?

The description is three sentences, front-loaded with the main action, and no unnecessary words. Every sentence provides value: purpose, side effects, and usage requirement.

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 simple mutation tool with no output schema, the description covers purpose, side effects, idempotency, and parameter origin. It does not mention error responses or failure modes, but the behavioral transparency is high otherwise.

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%, and the description adds context: chat_id comes from messenger_get_chats_v2, user_id defaults to Profile_id. It doesn't repeat dryRun or idempotencyKey descriptions already in schema, which is appropriate.

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 action: 'Marks the unread messages of the specified chat as read'. It specifies the resource (chat read) and the verb (marks). It distinguishes from siblings by noting it sends nothing to the other party and does not modify/delete messages, unlike similar messenger tools.

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?

The description explicitly states that chat_id comes from messenger_get_chats_v2, guiding the agent to first fetch chats. It also clarifies that the operation is invisible to the other party, setting expectations. However, it does not explicitly contrast with alternatives like messenger_delete_message or messenger_get_messages.

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