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

Annotations already declare readOnly=false, idempotent=true, destructive=false, and closed-world. The description adds the important behavioral detail that the write target is the *edit session*, not permanent library storage, which shapes what an agent expects afterwards; it omits failure/overwrite behavior, which is a minor gap given the idempotent hint.

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 short sentences, no filler, with the action and the caller constraint front-loaded. Every clause carries 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?

The tool has nested objects, a required opaque session id, and no output schema. The description explains the write target but leaves the session_id contract and the response/result of the save unstated, so an agent cannot fully predict the call's requirements or outcome.

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 only 50%: the `art` object is well documented in the schema, but `session_id` is an undocumented bare string and the description says nothing about where it comes from or what it identifies. With low coverage the description needed to compensate and adds zero parameter meaning.

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?

Specific verb and resource: saves the user's edits from the SpriteForge editor card into its edit session. It does not distinguish itself from sibling save_to_library or save_to_library-style operations, so the agent still has to infer which save path applies.

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?

"Only the card calls it" implicitly tells the agent this is an internal editor-driven write, which is useful context, but no explicit when-to-use/when-not or named alternative (e.g. save_to_library) is given. Usage is implied rather than stated.

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