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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds a valuable behavioral clarification (these are not IMAP Drafts-folder messages), which helps prevent misuse. It does not discuss pagination or body limits, but these are implied by the schema parameters (cursor, limit, bodyCursor, bodyMaxChars). Given the strong annotation coverage, the description adds sufficient context.

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 extremely concise: two sentences, no filler. The primary action is front-loaded in the first sentence, and the clarifying disclaimer is placed second. Every word earns its place, and the structure is ideal for quick scanning by an AI agent.

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?

The tool has 8 parameters with complex conditional constraints, but the input schema documents all of this thoroughly, and an output schema exists. The description covers the essential behavioral distinction (list vs. read, and non-IMAP). Given the schema richness, the description is adequate—it does not need to explain return values or detailed parameter interactions, as those are in the schema. Nothing critical is missing for an agent to call the tool correctly.

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 every parameter has a description in the schema. The tool description adds a note about the dual mode (list vs. read one draft via draftId), which helps understand the conditional logic (e.g., includeBody implies draftId). However, it does not elaborate on parameter usage beyond what the schema states. Per the rubric, with high schema coverage, the baseline is 3, and the description contributes only marginal value.

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 a specific verb ('List') and resource ('EPST draft summaries'), with an explicit alternate mode ('filter by draftId to read one draft'). It also provides a clarifying note that these are not IMAP Drafts-folder messages, which removes a common point of confusion. This clearly distinguishes the tool's purpose from related operations.

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 clear context: it is for listing EPST drafts or reading a single draft by ID. It implies the use case but does not explicitly name alternative tools (e.g., get_message) or state when NOT to use this tool. The non-IMAP remark serves as a caution, but there is no direct comparison to sibling tools. This is clear context without explicit exclusions.

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