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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description still adds real value beyond the annotations: the ordering guarantee (newest first) and that URLs are public and directly embeddable, which is exactly what an agent needs to know before using the result.

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 short sentences, front-loaded with what the tool returns, then how to use the output, then how to add images. No filler, and each sentence carries distinct information an agent would otherwise have to guess.

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?

No output schema exists, but the description compensates by describing the returned fields (public URLs) and their order, and by telling the agent how to consume them in HTML. The only residual gap is pagination/limit behavior for a large image library, which is minor for a simple read tool.

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% for the single 'limit' parameter, so the schema already documents its meaning, default and bounds. The description adds the ordering context implied by 'newest first' but says nothing about what happens when the limit is reached or whether results are paginated, so it stays at the baseline.

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 the specific resource (the user's saved images), examples of what's in it (logos, headshots, property photos), and the return contract (public URLs, newest first). It also names the two sibling tools that add images, so an agent can distinguish listing from creation without reading a 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 concrete usage context ('Use it as <img src=…> or CSS background-image in postcard, letter or email HTML') and explicitly routes addition to spur_upload_image (device) or spur_save_image (URL). It does not mention when listing is unnecessary or how deletion relates, but the routing guidance for the most likely confusion is explicit.

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