Advance a thread's subscription cursor to a given sequence number, confirming processed messages while keeping other threads visible and uninterrupted.
Advance a per-thread subscription cursor without hiding other threads.
| Name | Required | Description | Default |
|---|---|---|---|
| ack_seq | Yes | ||
| thread_id | Yes | ||
| binding_token | No | Opaque token returned by this agent's join_session or plan_session. Required for reliable identity when logical agents share an MCP connection. |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It discloses one meaningful trait—the operation will not hide other threads—but does not explain what happens to messages in the current thread, idempotency, ordering, or side effects. Some behavioral context, but clear gaps.
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 a single tightly worded sentence with no filler; the constraint 'without hiding other threads' earns its place. It is concise, though the brevity comes at the cost of omitted behavioral and parameter details.
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 3-parameter tool with no output schema and no annotations, this description is incomplete: an agent cannot determine when to use it, what ack_seq means, or what result to expect. It provides only the most basic operation and a single constraint.
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 only 33%, but the description adds no parameter-level detail. 'ack_seq' and 'thread_id' are left to be inferred from the tool's name and the phrase 'cursor', and binding_token is documented only in the schema. The description does not clarify whether ack_seq is inclusive, exclusive, required to be monotonically increasing, or what effect it has.
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 a specific action ('Advance') on a specific resource ('per-thread subscription cursor') and includes a distinguishing qualifier ('without hiding other threads'). It is clear enough to separate from sibling ack_messages/ack_delivery, though it doesn't name them.
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 phrase 'per-thread subscription cursor' implies the tool is for advancing a cursor for one thread's subscription, but there is no explicit when-to-use or when-not-to-use guidance and no mention of alternatives. Usage context is implied rather than stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.