Upload image

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

Annotations already declare non-readOnly, openWorld and non-idempotent, so safety is largely covered. The description adds real behavioral context beyond that: it names the storage destination and the return artifact (a hosted URL). It does not disclose upload constraints such as size limits, accepted formats, or what happens if the same image is uploaded twice (relevant given idempotentHint=false), which keeps it from a 5.

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?

Four short labeled blocks, front-loaded with purpose, zero filler. Every sentence carries information an agent acts on (what it does, what it is not for, what it returns, when to reach for it).

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?

With no output schema, the description correctly compensates by stating the return value is a hosted URL. Purpose, exclusions, and usage are all present for a three-required-parameter mutation. Only upload constraints (size/format) and duplicate-upload behavior are unaddressed.

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 67% and the description adds no parameter detail at all; it explains the resource and return value but never touches filename, contentType, or content. The schema documents content and contentType, so the baseline 3 applies, with the undocumented 'filename' parameter left as a minor gap.

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+resource ('Upload an image to Plunk's storage') and the output ('get back a URL usable in template and campaign HTML'). It explicitly distinguishes itself from the closest sibling behavior (inline attachments via plunk_send_transactional), so an agent can route correctly without opening any 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?

Both a 'Not for' exclusion and a 'Use when' condition are given, with the excluded case routed to the specific alternative tool and field (plunk_send_transactional's attachments field). This is explicit when/when-not/alternative guidance.

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