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

With no annotations, the description carries the full behavioral burden. It does add real value by disclosing the output format (transparent PNG) and a credit cost, but it says nothing about permissions/auth needs, rate limits, input format/URL accessibility constraints, or expected latency.

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, front-loaded sentences: purpose first, then output, then cost. Zero filler and nothing is buried.

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 simple 2-parameter tool with full schema coverage and no output schema, the description covers the essentials and even compensates for the missing output schema by naming the return artifact. It falls short only on input constraints (accepted image formats, URL size limits) and failure behavior.

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 both parameters (image_url, size with enum auto/small/hd) are already documented in the schema. The description adds no meaning beyond that, which matches the baseline of 3 for fully-covered schemas.

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 gives a specific verb and resource ("Remove background from any image") and additionally nails down the output ("transparent PNG") and cost ("2 credits"). An agent immediately knows what this tool does and what it produces; no sibling tool overlaps with this capability.

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?

Usage is only implied: the tool applies to "any image" reachable by URL. There is no statement of when to prefer it over alternatives (e.g., images or file-convert), no prerequisites, and no exclusions or limits on acceptable inputs.

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