upload_block

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

With no annotations, the description carries full burden. It discloses key behaviors: sync to Zwift/Garmin, the English requirement, the duration comparison check, pitfalls with nested repeats, and the idempotent re-run behavior. This goes well beyond a simple 'upload' and alerts the agent to potential silent failures.

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 three concise paragraphs, front-loaded with the primary purpose. Each sentence earns its place: sync destinations, language constraints, the duration-check warning, and idempotency. No redundant information, and the structure makes it easy to scan.

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?

The description covers all essential context for safe and effective use: external sync side effects, language expectations, the silent-failure warning, and update behavior. Since an output schema exists, return value documentation is not needed. The description is fully adequate for this tool's complexity.

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 100%, and the schema itself provides rich details for both parameters (e.g., block_name's update semantics, duration_minutes' comparison check). The tool description adds little parameter-specific meaning beyond what the schema already states, so the baseline of 3 applies.

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 opens with a specific verb and resource: 'Puts a block of planned workouts in the intervals.icu calendar.' It clearly distinguishes this from siblings like list_block, delete_block, and export_block by focusing on the upload/creation/update action. The additional sync details (Zwift, Garmin) further clarify its role.

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 explains when to use the tool (to put workouts in the calendar) and provides crucial guidance for correction: 'Re-run with the same block_name to correct; it creates no duplicates.' It does not explicitly mention alternatives or when not to use it, but the purpose is so distinct that an agent can infer usage. The warning about silent DSL mistakes also guides careful usage.

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