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

Annotations only declare readOnlyHint=true; the description goes far beyond by spelling out 'VIEW ONLY — you cannot click or control their screen', noting the return is an image plus its age, and describing polling and no-frame behavior. That is exactly the behavioral context an agent needs for a live-view tool.

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 purpose and return type, then adds prerequisites, polling cadence, and limits in short declarative sentences. Every sentence carries distinct, actionable information with no filler.

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?

There is no output schema, so the description carries the return-value burden and does so: an image, its age, and a 'no frame yet' note. Combined with the prerequisite state and polling guidance, nothing an agent needs to call this correctly is missing.

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?

The single action_id parameter is fully documented in the schema at 100% coverage, including that it comes from comms_action_create for a 'screen_share' action. The description's mention of the same provenance adds no new syntax or format detail, so it sits at the baseline for high-coverage schemas.

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 and resource ('See the LATEST screen frame from a screen_share action') and explicitly ties it to the sibling that produces the required id (comms_action_create). An agent can immediately distinguish this retrieval tool from the creation tool.

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 the precondition (recipient must have opened the link and clicked 'share screen'), the operating pattern ('poll this every few seconds to watch live'), and the expected empty-state ('no frame yet' until they start sharing). It also carves out what the tool cannot do, which prevents misuse.

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