Find widgets

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

Annotations already establish read-only, non-destructive, idempotent, closed-world behavior, so the description is not burdened with safety disclosure. It still adds real non-obvious context: results include the matched widget's subtree, and no-match is a valid empty result rather than an error, which shapes how the agent interprets an empty response.

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 tight sentences, zero waste, with the return scope front-loaded and the error-semantics caveat second. Nothing 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 agent still lacks a picture of the returned structure ('with its subtree' is only gestured at), and for a six-parameter, all-optional query tool the description never says whether the selector fields are ANDed, whether nth applies on top of them, or what happens when nth is combined with a selector. It is minimally adequate for a filtered lookup but leaves real 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 100%, so every one of the six selector fields (id, nth, role, label, value, label_contains) is documented in the schema with its matching semantics. The description adds nothing here beyond the vague word 'selector', which never explains how the fields combine or interact with nth — baseline 3 is appropriate.

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 names a specific verb (returns every widget matching a selector) and resource (widget, plus its subtree), which is clearly distinct from the sibling 'tree' or 'screen' that enumerate without a selector. It never names a sibling explicitly, so differentiation is implied rather than stated.

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?

'An empty result is not an error' is a behavioral note, not usage guidance. Nothing tells the agent when to reach for find instead of tree, screen, or status, nor what prerequisites (e.g., an existing tree/snapshot) must hold before the selector can match.

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