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

With no annotations, the description carries the full burden and does well: it discloses the output shape (a link per image to show the founder or download), that rendering matches App Store Connect's exact size, that the tool is free, and the behavioral quirk that caption text appears to count for App Store search since 2025 with the first three screenshots carrying the search result. It omits auth/rate-limit details but adds substantive context beyond the bare operation.

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?

Front-loads the core purpose, then layers in output, caption guidance, sibling routing, and pricing in a compact block with no wasted filler. Sentences are slightly dense with multiple ideas but remain readable and well-ordered.

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 generator with no output schema and no annotations, the description covers what the tool does, what it returns (a link per image), and how it fits with the uploader siblings. The main gap is that size options and image-source requirements are left to the schema, but overall an agent has enough to call it correctly.

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 50%, and the description adds meaning for the caption field (a benefit in searchable words, counts for search) and the optional second line, but says nothing about the size enum values, the required img source, or the bg/fg colors documented only in the schema. It partially compensates but leaves half the schema carrying the load.

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: renders New App Store screenshots with a caption (plus optional second line) over each raw screen at App Store Connect size, returning a link per image. It also distinguishes itself from siblings by noting that app_cpp and app_experiment perform the uploading, so the agent knows this tool generates rather than uploads.

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 clear routing context: this produces screenshots, while app_cpp and app_experiment upload them, and it advises writing captions as searchable benefits. It stops short of stating an explicit when-not condition, but the division of labor with sibling tools is clear enough to guide selection.

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