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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description contributes only that the returned record is 'full' (versus a preview) and that lookup is workspace-scoped; it says nothing about behavior for missing/unauthorized messages or cross-workspace access.

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?

A single short sentence with the resource and scope front-loaded and no filler. It is efficient but borders on under-specified given what the schema leaves undocumented.

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 simple two-parameter read tool with full annotation coverage and no output schema, the description is minimally sufficient. The remaining gap is the complete absence of parameter meaning in both schema and description, which an agent needs to supply IDs 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 0%, so the description must carry parameter meaning, and it largely does not. 'Within this workspace' loosely gestures at project_id but never explains why a workspace identifier is required alongside a globally unique message_id, nor does it clarify the UUID format or the failure mode if the two disagree.

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 gives a specific verb and resource ('Fetch one full message') and scopes it ('within this workspace'), which implicitly contrasts with list_messages' bulk listing. It stops short of naming any sibling explicitly, so the differentiation is inferred rather than stated.

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?

'One full message' hints that this is for retrieving a single record's complete content rather than enumerating messages, implying list_messages as the alternative. However, there is no explicit when-to-use statement, no note that message_id must come from a listing call, and no prerequisites mentioned.

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