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

readOnlyHint=true already tells the agent this is a safe read with no side effects. The description usefully adds matching semantics (all supplied words must be contained) and the size relationship for props, but says nothing about result limits, ordering, or what happens when nothing matches. With annotations covering safety, a 3 is right.

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 with no filler, front-loading the verb and matching rule. The parenthetical clauses make it slightly hard to parse, but nothing is wasted.

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?

For a 3-parameter tool with no output schema and only a readOnly annotation, the description conveys search semantics but leaves the return shape, count behavior, and empty-result handling unaddressed. Adequate but with clear gaps.

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 the description carries the burden for 3 parameters. It explains the 'words' matching rule and implicitly ties 'painting'/'object' to canvas/prop, but never mentions 'count' (max 20) or that all three parameters are optional by default. Partial compensation only.

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 ('Finds pictures to hang') and defines the matching rule ('whose words hold every word you give'), which is genuinely informative. It also names the two returned categories (paintings for a canvas, objects for a prop). It stops short of distinguishing itself from siblings like find_rooms or textures, so it isn't a 5.

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?

There is no stated condition for when to use this tool versus alternatives such as find_rooms, textures, or look. The phrase 'to hang' hints at intent but gives no explicit when/when-not guidance or prerequisites.

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