icloud-mcp

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

With no annotations provided, the description carries the full burden. It successfully discloses specific behaviors (automatic threading header management, subject prefixing, body format support) but fails to indicate critical safety properties like whether the reply sends immediately or saves as draft, or if the operation is reversible.

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 consists of three tightly constructed sentences with zero waste. It front-loads the core purpose (reply), follows with technical implementation details (headers), and ends with format support, earning its length.

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?

Given the 6 parameters with complete schema coverage and lack of output schema, the description adequately covers the primary function. However, with no annotations to indicate side effects or safety, the description should have disclosed whether this sends immediately or creates a draft, marking it as minimally viable rather than 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 fully documents all 6 parameters (uid, body, html, mailbox, replyAll, cc). The description mentions body format support but adds no semantic depth beyond what the schema already provides, meeting 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?

The description states the specific action (Reply) and resource (existing email) clearly. It distinguishes from siblings like compose_email and forward_email by mentioning Re: prefixing and threading headers (In-Reply-To, References), which are specific to reply semantics.

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 implicit context through mentions of threading headers and Re: prefixing, suggesting use for continuing conversations. However, it lacks explicit guidance on when to choose this over compose_email (new messages) or forward_email (forwarding), and states no prerequisites or exclusions.

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