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

No annotations, so description carries the full burden. It discloses an auth requirement ('Requires a bearer key'), which is valuable behavioral context. However, it doesn't mention append-vs-overwrite semantics, validation of readings, rate limits, or return behavior.

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 short sentences, front-loaded with purpose then auth requirement. No padding, though it is arguably too terse given the coverage gaps.

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?

A two-parameter write tool with no annotations, no output schema, and 0% schema description coverage. The description provides almost none of the missing behavioral or parameter context needed to call it correctly.

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 0%, so parameters are undocumented in the schema. The description doesn't explain site_id or the structure of readings array items, leaving both parameters semantically opaque for the agent.

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 (append water readings) and target (existing log), which clearly distinguishes it from sibling check_readings. Lacks detail on which log or units, but the core purpose is 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?

No explicit when-to-use vs alternatives (check_readings, get_log_summary). The 'existing log' constraint implies a prerequisite but doesn't state whether the log must already exist or how to create one.

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