get_data_source

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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds meaningful behavioral context beyond them: the response is orientation/capability material, not raw data, and it should shape how later data is interpreted ('its traps and how to record sessions on it'). No pagination or freshness/rate details, but for a zero-arg meta tool that is minor.

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 sentences, front-loaded with what the tool reveals and followed by the call-first instruction. The parenthetical capability list is dense but each item earns its place by telling the agent what signals are available before it queries them.

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?

With an output schema present, return values need no explanation, and with zero parameters there are no argument gaps. An agent knows what it gets, when to call it, and how to use the result, which is everything needed for this orientation tool.

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 tool takes zero parameters, so there are no semantics to document and the baseline is 4. The description correctly spends no space on arguments.

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?

Names a concrete resource and enumerates its contents specifically: connected wearable provider, its supported signals (readiness, sleep, HRV, coach plan, fitness trends), and its coaching guidance including traps and session recording. This clearly distinguishes it from siblings like get_readiness or get_coach_plan, which each return one slice of that data.

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?

'Call this first in a conversation and follow the guidance when interpreting data' gives an explicit sequencing rule and a downstream obligation, which is exactly the usage context an agent needs. It stops short of naming exclusions or contrasting with specific siblings, so it sits just below the top band.

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