Read MIO Message

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered, and the description usefully adds the return format ('complete message body as plain text') in the absence of an output schema. However, it never mentions the mark_read side effect (a read receipt sent to the sender) or behavior for unknown/inaccessible message IDs, which is the one genuinely non-obvious trait of this tool.

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?

Two sentences, zero padding, with the identity of the resource front-loaded and the return format appended as the last piece of information an agent needs.

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 two-parameter read tool with full schema coverage and no output schema, the description covers what it does, the scope ('any folder') and the return shape. The only material gap is the undisclosed read-receipt side effect of mark_read, which the description leaves entirely to the schema.

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 both parameters are already documented, and the description only echoes that lookup is by message ID. It adds no meaning beyond the schema and says nothing about mark_read, but with full schema coverage the baseline of 3 is appropriate.

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 (retrieve/read), a specific resource (a single MIO message by ID) and a scope qualifier ('from any folder') that distinguishes it from the list-oriented siblings get-mio-messages and search-mio-messages. It stops short of naming those siblings explicitly, so an agent must infer the split from context.

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 implied by 'single ... by its ID' versus the plural/query siblings, but there is no explicit when-to-use, when-not-to-use, or named alternative. An agent can infer it is the follow-up to a list/search call, but the description does not say so.

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