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

Annotations only declare the generic write/open-world profile; the description goes well beyond by disclosing the ownership-based authority model, persistence-until-deleted lifetime, the 4096-byte JSON payload cap, and a concrete rate limit. It also states that image bytes must be uploaded out-of-band and referenced by URL, which is real behavioral guidance not present in annotations or schema.

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 and persistence constraint are front-loaded, then authority, then renderer payloads, then limits — a sensible priority order for an agent deciding whether and how to call. The density is high but no sentence is redundant; every clause conveys a distinct constraint.

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 10-parameter mutation with an output schema and annotations already covering safety, the description supplies the pieces that matter: who is authorized, which renderers accept which payloads, size cap, persistence and rate limits. The reference to deletion implies the sibling management tools, leaving nothing an agent needs in order to call it 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?

With 60% schema coverage, the description usefully compensates for the largest gap by enumerating each renderer's data shape (text {body}, image {imageUrl,width,height}, embed {url} restricted to YouTube/Twitch/Twitter, link_preview {url}). It does not address label or explain the proof-related parameters, but those carry their own schema descriptions, so the residual gap is modest.

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?

Opens with a specific verb+resource+scope: "Post a PERSISTENT canvas update to a market you created." It immediately distinguishes itself from the nearest sibling by contrasting persistence against problee_publish_market_surface's ephemeral live slot, so an agent can separate the two without opening either schema.

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?

Gives the precise precondition for use (caller's bound/proven wallet must equal the market creator) and explicitly notes no markets:create scope is required, which removes a likely false blocker. It names the alternative tool and the condition that selects it, and adds an operational ceiling (10 updates/hour/wallet).

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