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

With no annotations provided, the description carries the full behavioral burden. It adds useful context by disclosing that returned URLs are ready and permanently valid, which goes beyond schema fields. However, it omits other relevant behavioral details such as authentication requirements, rate limits, pagination, or the exact return structure, leaving clear gaps.

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?

The description is two tightly written sentences with no redundant information. It front-loads the core action and then adds the optional filtering detail. Every sentence earns its place.

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?

There is no output schema, so the description is responsible for explaining return values. It does state that URLs are ready and permanently valid, which is helpful. However, it does not describe the overall return structure (e.g., array, metadata fields) or pagination behavior. For a simple list tool, this is minimally adequate but leaves gaps.

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 schema already documents both parameters thoroughly, including an example for album and an enum for format. The description simply repeats that filtering by album and format is optional, adding no new semantic meaning. Baseline 3 is appropriate when the schema does the heavy lifting.

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?

The description states a specific verb and resource: it lists images from the Systra Tools media library. It also clarifies the key output value (ready, permanently valid URLs). However, it does not explicitly differentiate itself from sibling tools like search_images, so it falls short of the top score.

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?

The description gives no explicit guidance on when to use this tool versus alternatives such as search_images. It implies usage through optional filters and the phrase 'to drop straight in', but does not state when-not to use it or name any alternative. This matches the calibration for a similar tool with no usage guidance.

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