preview

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

Goes beyond the annotations by disclosing the side effect ('Writes only a temp file, saves nothing to the output folder') and the return payload (temp path, warnings, preview). This usefully nuances readOnlyHint=true, which would otherwise suggest no filesystem activity at all. It stops short of describing failure modes or how warnings should be interpreted.

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 purpose, then the usage rule, then the side-effect/return disclosure. The middle clause ('so you can see why a label moved or a mark misses its element') is mildly verbose but earns its place by explaining the diagnostic value.

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 compensates by naming the return values (temp path, warnings, preview), and it points at the spec schema resource via the parameter definition. An agent has enough to invoke it and interpret the result 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 100%, so both 'look' and 'spec' are already documented in the schema (including the fallback-with-warning behavior for an uninstalled look). The description adds no additional parameter meaning, 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?

States a specific verb+resource ('Debug render of an annotate spec') and enumerates exactly what it draws (marks, cyan target rects, magenta label boxes). It is immediately distinguishable from the sibling 'annotate', which produces the deliverable rather than a diagnostic render.

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?

Explicitly says when to reach for it ('Use it when the annotate preview looks wrong') and when not to ('it is not a deliverable'), implicitly routing normal output generation to 'annotate'. Both the trigger condition and the exclusion are stated.

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