Update activity

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

Goes well beyond the annotations (which only carry readOnly=false, idempotent=true, destructive=true, openWorld=true). It discloses partial-update semantics ('what is not given is left as it is'), destructive replacement semantics ('the new text replaces the old'), and a genuine non-atomic failure mode: name and description are separate Garmin requests, so a failed second call leaves the first applied. That failure-mode disclosure is exactly the kind of behavior annotations cannot express.

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?

Three sentences, front-loaded with the core action, then alternatives, then the failure caveat. Every sentence carries distinct information; no restatement of the title or 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?

An output schema exists, so return values need not be explained. Combined with annotations covering the safety profile and the description covering partial-update, replacement, alternatives, and partial-failure behavior, an agent has everything needed to call this mutation correctly.

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 coverage is 100%, so the baseline is 3, but the description adds real meaning the schema does not: the nullable name/description parameters are optional and unspecified ones are left untouched, and any supplied value overwrites rather than merges. It stops short of describing format or length constraints, hence 4 rather than 5.

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+resource pair ('Rename an activity, replace its description, or both') and immediately delimits scope against two named siblings: edit_activity_sets for set-level edits and delete_activity for removal. An agent can distinguish this tool from every related sibling without opening a schema.

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?

Explicitly routes the agent: use edit_activity_sets for a strength session's exercises/reps/weights, use delete_activity to remove the activity. Both when-to-use and when-not-to-use are stated with the alternative named, leaving nothing to inference.

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