list_library_messages

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

Annotations already declare readOnlyHint: true, so the description does not need to emphasize safety. The description adds context about the types of messages listed and the purpose (finding IDs), which provides behavioral intent beyond annotations. However, it does not disclose pagination behavior or result ordering, which are relevant for a list operation.

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 two sentences, front-loaded with the action and resource. Every sentence serves a purpose: the first states what the tool does, the second gives a usage hint. No redundant or unnecessary words, highly efficient.

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?

For a list tool with 3 parameters and no output schema, the description covers the basic purpose and usage. However, it lacks details on the return format (e.g., fields like messageId, name) and pagination via offset. These are important for an agent to use the tool effectively, leaving some gaps.

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 explains each parameter. The description adds minimal extra meaning beyond mentioning 'library' which corresponds to libraryId. It does not elaborate on offset or category, so it does not significantly enhance understanding beyond the schema.

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 clearly states it lists messages in a library and enumerates types (email, survey, etc.). It also mentions a specific use case (finding messageId for distributions), which adds clarity. However, it does not explicitly differentiate from other list operations like list_library_blocks, though the name and context of message types help.

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 a specific usage scenario ('Use this to find messageId values for distributions'), giving some guidance on when to use the tool. It does not include when not to use it or mention alternatives like get_library_message for retrieving a single message. This is adequate but not thorough.

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