Mark a chat read or unread

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

Beyond the annotations, the description discloses that the effect is limited to the unread badge on linked devices and that no read receipts are emitted. This is meaningful behavioral context for a mutation that could otherwise be mistaken for a full read-status action.

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 short sentences, front-loaded with the primary action and the conditional. Every clause carries necessary information, with no filler or repetition.

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 idempotent toggle with rich annotations and full schema coverage, the description supplies the one missing behavioral nuance: it does not send read receipts. The agent has enough context to select and invoke the tool correctly.

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%, so parameters are already well documented. The description adds value by making the default behavior explicit: call without `unread: true` to clear the badge, or pass `unread: true` to set it unread.

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 names the exact action ('Clear' or 'set') and the resource ('the chat's unread badge'), and it explicitly contrasts itself with send_read_receipts. An agent can immediately distinguish this from the closest sibling tool.

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?

It states a clear when-not rule: 'Sends no read receipts; use send_read_receipts for blue ticks.' This is an explicit, actionable alternative that leaves no ambiguity about which sibling to choose.

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