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

The annotations already provide destructiveHint=true and readOnlyHint=false, so the mutating nature is known. The description adds the range of editable aspects but does not explicitly state that fields are replaced wholesale or that omitted fields remain unchanged; the schema's 'replacement' descriptions cover part of this, but the description itself adds limited behavioral depth.

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 with no wasted words. The trigger condition is front-loaded and the exclusion is concise and unambiguous.

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?

The description gives the agent enough to select this tool correctly, while the schema documents all 12 parameters, the output schema covers return shape, and annotations cover the destructive nature. It could add a sentence about replacement semantics or null-clearing behavior, but those are already present in the schema descriptions.

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 100%, so the schema already documents every parameter. The description's action words loosely map to parameters like title, startAt, endAt, location, and participantUserIds, but it adds no parameter-level detail beyond what the schema provides.

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 edits an existing Familia plan, with a concrete list of actions (rename, reschedule, move, update location, link tasks, change participants) that distinguishes it from creation or deletion. This is a specific verb+resource statement that an agent can act on.

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 tells the agent when to use the tool ('when the user asks to rename, reschedule, move...') and when not to use it ('Do not use to create a new plan'). This gives clear routing away from the sibling tool familia_create_plan.

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