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

With no annotations, the description carries the full burden and does disclose real behavioral constraints: accepted formats (png/jpg/webp), a 2 MB size cap, the two mutually exclusive input modes (public https URL vs. base64), and that the first screenshot becomes the cover. It stops short of stating permission requirements, what happens to existing screenshots, or failure behavior, which keeps it below 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?

Two tightly packed sentences with zero filler. The core action and format constraints are front-loaded, and the cover-image behavior plus the content guideline follow in the second sentence.

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 add-operation with no output schema and no annotations, the description covers what the agent needs to construct a valid call: input modes, formats, size limit, and cover semantics. It omits return/error behavior and whether the launch must be in a particular state, but those gaps are minor at this complexity level.

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 all three parameters are already documented in the schema. The description largely restates those constraints ('public https image_url', 'image_base64') and only adds the 2 MB cap, which is marginal value over the structured fields — baseline 3 applies.

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 names a specific verb and resource ('Add a screenshot to a launch') and immediately qualifies the accepted formats and size, so the agent knows exactly what operation this is. Sibling tools are all launch/tag CRUD operations, so there is little risk of confusion, but the description never explicitly contrasts itself with them.

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 implied by 'Add a screenshot to a launch', and the 'Use real screenshots of the product, never made-up ones' line is a genuine content guideline that steers the agent away from generated placeholders. However, there is no when-to-use vs. when-not-to-use guidance, no mention of prerequisites (e.g., must the launch be a draft?), and no named alternative tool.

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