Add a screenshot

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

Annotations already declare non-idempotent, non-destructive, open-world writing, but the description adds the meaningful quota constraint ('5 at most') and warns that repeated calls accumulate screenshots. That accumulation behavior is exactly the consequence an agent needs beyond the idempotentHint flag.

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?

Two sentences, no filler, with the quota limit and the non-idempotency warning front-loaded. Every clause carries actionable 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 simple single-item add tool with full schema coverage and safety annotations, the description covers sources, quota, and repeat-call risk. It does not describe the return value, a minor gap given there is no output schema.

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%, so the baseline is 3, but the description adds real semantics: url and file_path are alternative sources, and local file use requires the npx package. That packaging constraint is not conveyed by the schema alone.

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?

Specific verb and resource ('Adds one screenshot to a project'), with scope limits (5 at most) and supported sources (public URL or local file via npx). Clearly distinguishable from siblings like set_logo and remove_image.

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 concrete usage rule: 'Each call adds another one, so do not repeat a call that succeeded' — a practical when-not-to-repeat instruction. It does not explicitly name alternative tools or state prerequisites (e.g., needing an existing project), but the context for calling it is clear.

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