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

There are no annotations, so the description carries the full burden. It states that it decodes base64url, writes to disk when path is set, and returns size, filename, attachmentId, and standard base64. This is useful behavioral disclosure, though it leaves some edge behavior (e.g., directory vs file path handling, errors) unspecified.

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 three sentences with no filler. It front-loads the core purpose, then adds valuable technical context about the workaround, decoding, disk writing, and return values. Every sentence earns its place.

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?

With no output schema and no annotations, this definition is reasonably informative but still incomplete. It covers the main behavior and return fields, but leaves path semantics ambiguous ('file (or directory)'), does not explain the filename parameter, and does not address authentication or failure modes. It is adequate for basic invocation but not fully self-contained.

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 only 25%, so the description must compensate. It reinforces the path parameter behavior, but it does not explain the expected roles of messageId, attachmentId, or filename. The names are suggestive, but the description does not clarify how these inputs map to the API call or how filename interacts with path.

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 identifies the verb and resource: 'Download Gmail attachment bytes' with the specific API endpoint. It is immediately obvious what the tool does even though the sibling tools (list_send_as, send_as) are unrelated. It does not explicitly differentiate from those siblings, but the explicit endpoint and comparison to 'Stock Gmail MCP' provide strong clarity.

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 gives clear context for use: use this tool when attachment bytes are needed, especially because 'Stock Gmail MCP cannot return file bytes.' It does not provide explicit exclusions or say when not to use it, but the context is sufficient to guide an agent for this Gmail attachment scenario.

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

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

No annotations are provided, so the description carries the transparency burden. It discloses that this is a read-only GET operation, which is helpful, but it does not mention authentication requirements, pagination, rate limits, or the response shape. Adequate for a trivial list call, but not rich.

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 dense sentences: the first defines the action and endpoint, the second scopes usage against alternatives. There is no filler or redundant restatement of the tool name.

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 zero-parameter read-only list operation with no output schema, the description is mostly complete: it names the endpoint and gives selection guidance. It does not describe the return value shape, which would have been helpful given the absence of an output schema, but the operation's simplicity keeps the gap small.

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?

The tool has zero parameters and an empty input schema, so the description does not need to explain parameter meanings. Per the baseline for zero-parameter tools, the endpoint and listing scope provide enough context.

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 uses a specific verb ('List'), a specific resource ('Gmail sendAs aliases'), and the exact API endpoint (GET users.me.settings.sendAs), making the tool's purpose unmistakable. It also implicitly differentiates itself from the sibling get_attachment and from stock Gmail MCP by scoping the plugin to sendAs and attachment work.

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?

It gives clear guidance: 'Use this plugin only for sendAs + attachment bytes' and explicitly says to use 'stock Gmail MCP for inbox search, labels, and triage.' This names an alternative for other tasks, though it does not explicitly distinguish list_send_as from the closely named sibling send_as.

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

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

With no annotations present, the description carries the full disclosure burden and does well: it states the encoding (RFC2822 MIME raw, base64url), the return shape (message id and threadId only), and a security-relevant guarantee ('never tokens'). It does not cover error behavior or sending limits, but the most important behavioral facts are disclosed.

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 dense sentences with no filler: purpose and encoding up front, then required/optional params and return behavior. Every clause earns its place, including the non-obvious 'never tokens' caveat.

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 7-parameter, no-annotation, no-output-schema send tool, the description supplies the full calling contract: required fields, optional fields, encoding, and return value. The main gap is error semantics (invalid alias, auth failure), but nothing an agent needs to construct a valid call is missing.

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 57%, and the description adds some meaning: it clarifies that at least one of body/html is effectively required despite the schema listing only from/to/subject as required, and it labels cc/bcc as optional. However, it mostly restates schema-provided facts (alias email for from, HTML with or instead of body) and leaves cc/bcc/subject value formats to inference.

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 opens with a concrete verb+resource — 'Send mail From a Workspace sendAs alias' — and names the backing API method (users.messages.send). This clearly sets it apart from siblings list_send_as (enumerate aliases) and get_attachment (retrieve a file), so an agent can route correctly without opening the schema.

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?

It enumerates the exact invocation contract: required from (alias), to, subject, and body text and/or html, with cc/bcc optional. This is clear context for calling. It stops short of explicit exclusions like 'use list_send_as to discover valid aliases first', so it doesn't quite reach a 5.

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