measure

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

Annotations declare readOnlyHint=true and idempotentHint=false; the description adds the non-obvious side effect that 'points are marked on screen', which explains the non-idempotency (visible markers accumulate). It stops short of saying how long markers persist or how results are reported.

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 dense sentence, front-loaded with the primary operation and listing modes/outputs without filler. Slightly compressed by the line wrap, but every clause carries 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?

No output schema exists, so the description compensates by enumerating returned quantities (lengths, dx/dy, angles, total, area, radius). It lacks detail on the coords parameter's effect on results and on the returned format, which leaves a small gap.

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%, so baseline is 3, but the description adds meaning beyond the schema: it maps 'three or more points' to area calculation and associates handle with length/area/radius, whereas the schema only says 'Two or more points' generically.

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 and resource ('measure distances... between points', 'an entity's length/area') with concrete outputs enumerated (segment lengths, dx/dy, angles, area). It is distinguishable from siblings like inspect/find/mark in intent, though it does not name them 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?

The three operating modes (2+ points → distance, 3+ points → area, handle → entity measurement) imply when each pathway applies, but there is no explicit statement of when to prefer this over inspect/find or what to do when both points and handle are omitted.

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