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

Adds substantial behavior beyond the annotations: only provided fields change, null clears a field, concurrent changes are preserved unless they touch the same field, and hidden/surprise items cannot be changed. This is exactly the kind of mutation and conflict behavior an agent needs before calling the tool.

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 short sentences, front-loaded with purpose and partial-update semantics, then the sibling alternative, concurrency behavior, and the hidden-item restriction. No sentence is redundant.

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 mutation tool with an output schema and safety annotations, the description covers purpose, partial update behavior, conflict handling, and a key restriction. It is not fully complete on field-level parameter semantics, but the core invocation behavior is adequately described.

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 20% across 15 parameters, so the description must compensate. It usefully explains partial-update and null-clearing semantics, but does not clarify the many field-level parameters such as timeZone, endTimeZone, provider IDs, or end fields beyond what their sparse schema entries say.

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?

States a specific verb and resource: changes an activity's details, with precise partial-update semantics. It explicitly routes movement/reordering to move_activity, so the agent can distinguish it from the most confusable sibling without opening schemas.

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 a clear condition for using update_activity (changing details) and names move_activity as the alternative for moving to another day/lane or reordering. It does not discuss when to prefer add_activity or remove_activity, but the alternative for the main ambiguity is explicit.

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