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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds value by noting that annotations expire after ~1 day and that the tool returns an image. It does not mention error cases (e.g., expired annotation), but the extra context is useful beyond what annotations provide.

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?

Three short sentences with no fluff. The most important info (what it does and where the id comes from) is front-loaded, and the expiration note is placed at the end. Every sentence earns its place.

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 read-only tool with two string parameters and no output schema, the description covers the main behavior and return value. However, it leaves projectId undefined and does not mention what happens when an annotation expires or if the id is invalid. These gaps reduce completeness for an agent trying to use it reliably.

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 0%, so the description must compensate. It gives meaning to annotationId by pointing to get_current_context, but projectId is left completely unexplained. This partial compensation is insufficient for a required parameter, but the one semantic clue is helpful.

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 clearly states the action ('View a screenshot annotation') and resource ('the user drew on the app preview'), and clarifies the return value (annotated image). It does not explicitly distinguish from siblings like get_current_context, but it implies a complementary relationship rather than a replacement, so it is clear enough.

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?

The description gives a key usage hint: 'annotationId comes from get_current_context', which tells the agent to call that tool first. However, it does not explicitly state when to use this tool over alternatives, nor any exclusions or conditions. The guidance is implied rather than explicit.

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