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

Goes well past the annotations by disclosing pricing (3 credits per call), the sk_live_ key requirement, that mcp-credit-gateway charges before forwarding, rate limiting, that every attempt including failures is logged with an audit id, and that bulk misuse may be blocked or reported. These are exactly the operational and consequence details an agent needs before committing to a destructive, non-idempotent call.

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 first half is well front-loaded, but the metering/audit/audit_id information is stated two or three times across the English paragraph, the parenthetical Chinese sentence, and the closing sentence. That redundancy costs space without adding 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?

For a single-image metered mutation with no output schema, the description covers input constraints, mask modes, authorization gates, cost, and the fact that an audit_id comes back. Nothing an agent needs to call it correctly or safely is missing.

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 already 100%, so the baseline is 3; the description still adds cross-parameter behavior the schema does not encode — that mask_image_url and mask_rect are alternatives and that omitting both falls back to upstream auto-detect, whose availability is upstream-dependent. It also restates the mask polarity (white = remove) and the 0–1 normalization, though that duplicates the schema.

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 a specific verb and resource ("AI watermark removal / inpainting") plus hard scope: ONE image, JPG/PNG/WebP, <=10 MB, public URL. An agent can immediately distinguish this from the sibling add_watermark and from the blind-watermark tools.

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 a strong when-to-use condition (only owned or explicitly licensed/authorized material) and explicit exclusions (no copyright/attribution stripping, no bulk third-party removal). It also explains the mask-mode selection: mask_image_url, mask_rect, or neither for upstream auto-detect. It does not name a sibling tool as an alternative path, which keeps it below 5.

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