add_activity_message

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

Annotations already indicate idempotentHint=false and destructiveHint=false. The description adds context beyond this by explaining the activity is a 'conversation thread' and that the purpose is feedback, which helps the agent understand the operation's side effects. It does not contradict annotations and offers useful behavioral context without duplicating the 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?

The description is concise and well-structured. It leads with the primary purpose, follows with usage guidance and an alternative, and ends with a clear parameter list. Every sentence earns its place with no wasted words or repetition of annotations.

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 simple two-parameter tool with full schema coverage and an output schema, the description completely captures what an agent needs: purpose, usage context, and an alternative. The description is sufficient for correct invocation without requiring additional inference.

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?

The schema covers 100% of parameter descriptions, so the description's 'Args' section simply mirrors the schema without adding new meaning. The baseline of 3 applies because the description doesn't provide extra format, constraints, or relationships beyond what the schema already states.

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 action, resource, and scope: 'Post a comment/note to an activity conversation thread.' The verb 'post' and the specific resource 'activity conversation thread' make the tool's purpose unmistakable. It also distinguishes itself from the sibling tool 'update_activity' by explicitly noting the alternative for editing descriptions.

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 provides explicit usage guidance: 'Use to add athlete/coach feedback to a workout.' It also gives an alternative: 'To edit activity description directly, use update_activity instead.' This clearly tells the agent when this tool is appropriate and when it is not, directly addressing tool selection.

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