Update an activity

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

The annotations already establish that this is not read-only and not destructive, but the description adds a meaningful behavioral detail: it performs a partial update and leaves unspecified fields untouched. This prevents an agent from assuming omitted fields are reset to defaults, which is valuable beyond the annotation hints.

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 compact sentences: the first states the action and scope, the second clarifies update semantics. Every phrase earns its place, and the most important information is front-loaded.

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 partial-update mutation tool, the description covers the resource, the editable fields, and the key behavioral rule. The output schema and annotations cover return behavior and safety, and the schema documents the required id. It could be slightly more complete by noting how to obtain the id, but that is already present in the schema parameter description.

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?

With only 56% schema description coverage, the description compensates by naming nearly every parameter in natural language, including 'perceived exertion (RPE)', 'feel', 'tags', and 'race/commute flags'. It helps map user intent to schema field names, though it does not add constraints or replacement semantics that are already in the schema.

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 uses a specific verb ('Edit') and resource ('a completed activity'), then enumerates the exact editable fields. This clearly separates it from create/get tools in the sibling list, such as create_manual_activity and get_activity.

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 phrase 'Edit a completed activity' implies the tool is for modifying an existing activity rather than creating one, and 'Only the fields you pass are changed' gives useful update semantics. However, it does not explicitly state when to prefer this over sibling tools like update_workout or create_manual_activity, nor does it provide exclusions.

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