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

Goes well beyond the annotations: names the tracer (VTracer, MIT), discloses that alpha is flattened to white, caps output at 2 MB / 2000 paths and makes it script-free, states a 45 s ceiling, and covers billing (USD 0.005, failures not charged, no free tier) and privacy (images not logged). This is exactly the context the readOnlyHint/destructiveHint flags cannot convey.

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?

Purpose is front-loaded in the first clause and nearly every sentence carries a distinct constraint. The tail is telegraphic and slightly cluttered (stray double period, back-to-back one-liners for latency, price and tier), but no sentence is filler.

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 paid, bounded compute tool with an output schema handling return values, the description covers inputs, limits, output lifetime, cost and failure semantics. An agent can decide and call without opening anything else.

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 the five parameters are already fully documented, including the 262144-pixel cap and the url-vs-base64 retention. The description restates the pixel cap and the 24-hour url behavior but adds no syntax or edge-case detail the schema lacks, 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 and resource ('Vectorize a raster image to SVG paths') plus the accepted input formats and the underlying engine. The line 'Approximate; not OCR' explicitly carves it apart from the ocr_image sibling in the same catalog.

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?

'not OCR' functions as a when-not rule, and 'output=url keeps the result 24 hours' tells the agent which output mode suits a follow-up fetch. It stops short of naming the alternative tools (ocr_image, image_convert, pdf_rasterize) that an agent would otherwise have to guess between.

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