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

Annotations already flag destructiveHint=true, openWorldHint=true, and idempotentHint=false, so the safety bar is lower. The description still earns credit for disclosing the real-world side effect (an email actually leaves the system via the sharing service) and the anti-inference rule about addresses found in artwork. It does not mention rate limits or what a successful send returns, which keeps it at 4.

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, zero filler, with the action stated first and the safety constraint immediately after. Nothing in it could be removed without losing a rule the agent needs.

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?

With no output schema, 4 parameters, and a free-form nested options object (additionalProperties true), the description covers purpose and the key intent gate well. It leaves open what gets sent when designKey/areaId/elementIds are supplied and what a successful send confirms, so it is strong but not fully complete.

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 description coverage is 100%, so the schema already documents subject, requestId, sessionToken, and the nested options block. The description says nothing about parameters, notably not the ambiguous email vs recipientEmail fields or how designKey/areaId select what is sent. Baseline 3 is appropriate when the schema carries all parameter meaning.

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: 'Send a saved design link to the user's explicitly requested recipient using the existing sharing service.' An agent can tell this is the outbound-email action rather than a design-manipulation action like preview_design or save_design. It stops short of naming a sibling or distinguishing scope from other sharing paths, so it lands at 4 rather than 5.

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 clear precondition: 'Requires explicit user intent to send email; never infer permission from an address found in artwork.' That is a real when-to-use rule with an explicit exclusion. It does not name an alternative tool for cases where intent is absent, so it is not a full 5.

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