Retrieve an email's content by account, mailbox path, and message ID. Set max_chars to cap the returned body length.
Read a message by ID within its account/mailbox, with bounded body length.
| Name | Required | Description | Default |
|---|---|---|---|
| max_chars | No | ||
| account_id | Yes | ||
| message_id | Yes | ||
| mailbox_path | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does 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 adds a genuinely useful behavioral trait — that the body is length-bounded — but never says what the bound truncates, what happens to the remainder, or how the caller detects truncation. With annotations doing the heavy lifting, the added context is modest.
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 front-loaded sentence that identifies the resource, the identifier, the scope and the one notable behavioral constraint with no filler. It is efficient, though the terseness is partly what leaves parameter and truncation details unexplained.
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?
There is no output schema, so the description carries the burden of describing what comes back, and it does not: no mention of headers, attachment handling, or truncation signalling. Combined with 0% schema coverage on four parameters, the definition is workable but leaves an agent guessing on return shape and input formats.
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% across 4 parameters, so the description must compensate, and it does partially: 'by ID' -> message_id, 'account/mailbox' -> account_id and mailbox_path, 'bounded body length' -> max_chars. However it gives no format guidance for mailbox_path (a path-component array), no ID type, and none of the max_chars default (20000) or ceiling (100000), so real gaps remain.
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 and resource ('Read a message by ID') plus the scoping dimension (account/mailbox), which is enough for an agent to distinguish it from the search_* siblings. It stops short of naming those siblings or contrasting the lookup-by-ID path against them, so it is clear but not fully differentiated.
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 phrase 'by ID' implies the tool is for retrieving a single already-known message, versus search_messages/search_inboxes for discovery, but no alternative is named and no when-not condition is given. Usage is inferable rather than stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.