update-planner-plan

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

Annotations already declare destructiveHint=true and openWorldHint=true, so the safety profile is covered; the description adds genuinely new protocol context by disclosing the mandatory If-Match/ETag concurrency check and where to source it. It does not state what happens on an ETag mismatch (412) or whether the update is a merge or full replace, and the noted If-Match requirement has no corresponding parameter in the schema, which weakens the disclosure.

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 sentences, front-loaded with the purpose and then the hard prerequisite. The '💡 TIP: CRITICAL:' prefix is noisy labeling but the content underneath earns its place.

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 destructive, nested-body mutation with no output schema and an 80%-covered schema, the description covers the ETag precondition but omits conflict semantics and mutation scope (merge vs replace, which nested collections like tasks/buckets are ignored). The unactionable ETag note with no matching parameter leaves the agent unsure how to actually satisfy the requirement.

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 description coverage is 80%, so the schema already documents body/plannerPlanId/confirm/includeHeaders/excludeResponse well. The description adds no field-level meaning (nothing about which body properties are mutable, e.g. that owner and tasks are read-only) beyond what the schema states, so baseline 3 applies.

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?

Names a specific verb ('Update') and a specific resource ('plannerPlan object'), which cleanly separates it from create-planner-plan, get-planner-plan and the task/bucket updaters in the sibling list. It never explicitly contrasts itself with update-planner-task or update-planner-bucket, so it stops short of a 5.

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?

Gives the operational precondition for calling it — you must first call get-planner-plan with includeHeaders=true to obtain the ETag — which is real routing/sequencing guidance. It offers no when-not-to-use case or alternative (e.g. changing a task vs a plan), so no exclusions are stated.

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