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

Annotations only declare readOnlyHint=true, so the description carries real weight: it discloses that the interface actually executes in a runtime, that the response is either an error or a rendered-text preview, and that every src: image is fetched as the recipient's app would be, with per-image failure reasons. It stops short of describing the shape of the error output or any runtime limits, so it is strong but not exhaustive.

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?

Three sentences, front-loaded with the core action, which is good structure. However the writing is loose — 'answers the error' is an odd construction and the em-dash clause about images is overloaded — so clarity suffers more than length does.

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 correctly compensates by explaining both return modes (error vs. preview plus image-failure list). For a one-parameter read-only check tool that is close to complete; only output structure details and any runtime constraints are left implicit.

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 single parameter is already documented in the schema as 'Smalltalk source ending in a ScreenMorph (see get_ui_guide).' The description adds no further detail about the ui string itself, so the baseline 3 applies.

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 and resource ('Run a request's interface in the Taskriz runtime') and says what comes back: an error answer or a plain-text preview. It clearly distinguishes itself from send_request, though the phrase 'answers the error' is grammatically loose and slightly obscures the outcome for an agent.

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?

It names send_request as the alternative and gives the selecting condition — send_request also checks the interface, but this tool is for use 'while writing' (iteration) and for fixing broken images 'before sending.' That is explicit routing, though no when-not-to-use case or prerequisite is stated.

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