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

Annotations already declare readOnlyHint=true and the description's 'Read' is consistent with that. It adds that both body and metadata are returned, but says nothing about permissions, message-size limits, or what happens with an invalid/expired id — modest added value against an already-covered safety profile.

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?

One front-loaded sentence that states verb, resource, return content, and lookup key with zero filler. Nothing could be cut without losing information.

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 one-parameter read tool with annotations covering safety and no output schema, the description covers what is returned (body + metadata) and how to address the message. Missing only edge-case behavior for invalid ids or large messages.

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 coverage is 100% and the single parameter is documented with its origin ('UUID from mAYL_send or inbox'). The description repeats the name but adds no format or error semantics beyond the schema, so baseline 3 applies.

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?

States a specific verb ('Read') and resource ('full body and metadata of an email') plus the lookup key ('by message_id'). This clearly distinguishes it from mAYL_list, though the description never names that sibling explicitly.

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?

Usage is only implied: the emphasis on 'full body' suggests it is for retrieving content after a listing call, and the schema note says the id comes 'from mAYL_send or inbox'. There is no explicit when-to-use versus mAYL_list/mAYL_events guidance or stated preconditions.

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