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

Without annotations, the description carries the full behavioral burden. It discloses fusion behavior, partial-data tolerance, cross-session tracking via subject_id, confidence impact from source_device, and a non-medical disclaimer. It does not cover error conditions, idempotency, or rate limits, so it falls short of a 5.

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?

Front-loaded with the core action and required inputs, then uses short bullets for common signals and trigger memory. Every sentence adds value; the only minor inefficiency is the long list of signals that could be trimmed, but it remains readable.

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?

Given 37 parameters, no output schema, and no annotations, the description provides essential context: required fields, signal categories, return shape ('same fields as get_human_state plus signals_received and topics_detected'), and trigger-memory guidance. It is largely complete, though it omits behavior for unrecognized signals and does not explain most of the 35 optional parameters.

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 0%, so the description must compensate. It documents required fields (session_id, timestamp ISO 8601) and gives meaning, units, and ranges for several key signals (heart_rate 30-220 bpm, rmssd, tone enums, sentiment -1.0 to 1.0, expression enums). With 37 parameters, many others (e.g., eda, spo2, eeg powers) are left undocumented, so it does not fully close the gap.

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 states a specific verb and resource: 'Send biometric signals from any sensor, get unified state back.' This clearly distinguishes it from read-only siblings like get_human_state or get_session_history. The tool's ingest-and-fuse action is unmistakable.

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?

It states required inputs and the 'send whatever you have' flexibility, but it does not explicitly contrast with alternatives or mention when not to use it. The absence of sibling callouts keeps it from a 5, but practical guidance is clear.

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