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

Beyond the annotations (destructiveHint=true), the description discloses critical behaviors: the confirm parameter requirement, MCP's conversion of emailBodyText to content.root, the hard business-permission gate, and the grace-period/resubscribe workflow. It thoroughly explains what the agent must check and show to the user, far exceeding the annotation signal.

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?

The description is front-loaded with the core purpose and then packs essential operational details into a few sentences. Each sentence contributes value (confirm requirement, content options, permissions, warning). It is slightly dense but not wasteful given the tool's complexity.

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?

Despite the destructive annotation and complex schema, there is no output schema and many parameters are undocumented. The description covers the most critical access-related context but omits return behavior, dueAt semantics, and how scheduling relates to immediate sending. An agent would struggle to correctly populate all inputs, so completeness is low.

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 only 18%, and the description compensates for only a few parameters (confirm, emailLexicalContent, emailBodyText). It does not clarify the required parameters communityId, messageId, or the dueAt format, leaving the agent to guess. For a tool with 22 parameters, this is a significant gap.

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 opens with a specific verb and resource: 'Schedule a Magic Reach message.' This clearly states the action and distinguishes it from siblings like send_magic_reach_message or create_magic_reach_message. The purpose is unambiguous and immediately understandable.

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 provides explicit preconditions: 'Requires confirm set to SCHEDULE' and mandates calling check_business_tool_access before collecting inputs. It also gives when-not-to-use guidance by stating 'FREE businesses cannot use this tool' and 'never proceed when access is blocked.' It does not explicitly name alternative tools, which is why it falls short of a 5.

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