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

Even with the `idempotentHint` annotation (which is true), the description adds valuable behavioral context: it explains the side effect on parent nodes ('the parent is auto-updated') and what the tool returns ('Returns the current subtree state'). It also mentions the required permission ('Requires memory:write or full permission'), which is beyond what the annotations provide. The `idempotentHint` is consistent with the update semantics.

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?

Four sentences, each carrying weight. The first sentence states the primary purpose, the second covers side effects, the third mentions permissions, and the fourth and fifth give usage direction and parameter format. Only minor redundancy (the UUID/GUID note could arguably be in the schema), but overall tight and well-structured.

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?

Given the moderate complexity (5 params, no output schema, annotations present), the description covers the essential side effects and permission requirements. It doesn't explicitly state what the return value looks like beyond 'the current subtree state', but the description's mention of that return is sufficient for an agent to understand the nature of the operation. It could mention error cases, but that's likely beyond scope.

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?

The input schema already has 100% description coverage for all 5 parameters, so the baseline is 3. The description doesn't add extra parameter-level semantics beyond what's already in the schema, but it does provide general context about `playbook_id` format and the tool's purpose. Since the schema handles the parameter documentation well, this is adequate.

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's purpose: 'Update the status of a task node in a hierarchical plan.' It uses a specific verb ('update') and resource ('task status in a hierarchical plan'), and adds crucial context about auto-updating parents. This effectively distinguishes it from similar update tools like `update_playbook` or `update_run`.

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 says when to use this tool ('Use create_task_graph to build the plan, not this tool'), which directly addresses the sibling tool `create_task_graph`. It also instructs on the required parameter format ('Pass playbook_id as the UUID or GUID'), making it exceptionally clear when and how to use it. The note about the alternative tool is a model example of usage guidelines.

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