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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description still adds real value by disclosing what the response carries — location, network, license, quality check with rating and reasons, latest reading — which is the only statement of return contents since there is no output schema. Not-found/error behavior and whether the latest reading can be absent are left unstated.

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?

A single front-loaded clause naming the identity key first, then the returned fields. No filler, no restatement of the title, nothing that could be cut without losing information.

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 no output schema, the description does the work of telling the agent what comes back, which is the main gap it needed to fill. The remaining omission is failure semantics (invalid or unknown id) and nullability of the latest reading, minor for a read-only lookup.

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% and the schema itself explains that the id comes from find_sensors, so the description's 'by its id' adds nothing new. Baseline 3 applies for a single fully documented parameter.

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?

States a specific verb+resource ('One sensor by its id') and enumerates the payload it returns: location, network, license, quality check with rating/reasons, and latest reading. That is enough to separate it from find_sensors (discovery) and get_sensor_readings (time series), though it never names those siblings explicitly.

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?

Usage is only implied: the schema note 'Sensor id from find_sensors' hints at the find-then-get sequence, and 'by its id' implies single-record lookup rather than listing. There is no explicit when-to-use/when-not or stated alternative for fetching readings.

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