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

Annotations already declare readOnlyHint=false and destructiveHint=false, and the description adds genuinely new behavioral facts on top: the event is shared/visible to all household members, and 'Commits immediately' tells the agent there is no draft or confirmation step. It does not address conflict handling, notifications to members, or whether the write can be undone, which keeps it below 5.

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 with the sharing scope and the immediate-commit behavior front-loaded. Every clause carries information; nothing is redundant with the title or the schema.

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 four-parameter mutation with no output schema, the description covers the two most important behavioral facts (shared visibility, immediate commit). It leaves out timezone/scheduling semantics, member notification behavior, and any conflict or validation outcome, so it is adequate but not complete for a write tool.

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 only 50% — starts_at and ends_at carry ISO 8601 format notes, but title and description are bare strings. The description adds no parameter-level meaning at all (no timezone note, no length or content guidance for title/description), so it fails to compensate for the coverage gap.

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 states a specific verb and resource ('Create a SHARED household calendar event') plus a scope qualifier ('visible to everyone'), so the agent knows exactly what object is being produced. It stops short of differentiating itself from neighboring creation tools such as create_reminder or create_availability_block, which is why it is a 4 rather than 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?

There is no explicit when-to-use or when-not-to-use guidance, and no named alternative for scheduling needs that are not household-wide. The only usable signal is implicit: 'SHARED' and 'visible to everyone' suggest this is for common-knowledge events, but the agent must infer that on its own.

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