start_activity

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

With no annotations, the description carries the full burden. It does disclose the fuzzy matching behavior for type_name and the backdating capability via `at` or started_minutes_ago, which is useful. However, it does not disclose what happens if an activity is already running (e.g., whether it is replaced or rejected), nor any side effects or preconditions, leaving gaps in transparency.

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 two sentences, front-loaded with the primary action, and each phrase contributes meaning (fuzzy matching, list_activity_types pointer, backdating options). No filler, ideal conciseness.

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 the main usage patterns effectively: how to specify the activity type and how to backdate. Minor gaps exist, such as not explicitly stating mutual exclusivity between type_name and type_id, and not clarifying behavior when called during an active activity. Given the tool's simplicity, it is mostly complete.

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%, giving a baseline of 3. The description adds value by introducing the "fuzzy matched" behavior for type_name (not present in schema), explicitly framing type_name and type_id as alternatives, and clarifying that `at` is wall-clock. This goes beyond schema descriptions.

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 tool's function: "Start tracking an activity" with specific methods (by type name or type_id). It distinguishes itself from siblings by focusing on the start action and references list_activity_types for type resolution, making the purpose unambiguous.

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 clear context for when to use the tool: to begin tracking an activity. It also points to list_activity_types as a prerequisite for type_name, which helps the agent. However, it does not explicitly mention alternatives like stop_activity or log_interval or exclusions, so it lacks the explicit when-not guidance of a 5.

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