smtp_finderLook up SMTP server settings (host, port, encryption) for a given email provider. Use this to find the correct SMTP configuration for services like Gmail, Outlook, SendGrid, etc.
| Name | Required | Description | Default |
|---|---|---|---|
| provider_name | Yes | The email provider name to look up, e.g. gmail, sendgrid, mailgun, outlook |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the agent knows it is a safe read operation. The description adds that it returns host, port, and encryption, but does not disclose additional behaviors such as network dependency or error handling. No contradiction with annotations.
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, front-loaded with the action, and includes all necessary information without fluff. 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?
The tool is simple with one parameter and no output schema, yet the description still mentions the expected return fields (host, port, encryption). It provides a clear scope for supported providers. Minor omissions like unsupported providers or error cases are acceptable given the simplicity.
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 schema description covers provider_name with examples (gmail, sendgrid, etc.), and the description reinforces this with examples like Gmail, Outlook, and SendGrid. No new meaning is added beyond what the schema already provides, so baseline 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?
The description uses the specific verb 'look up' and identifies the resource as 'SMTP server settings (host, port, encryption)' for an email provider. It then gives examples (Gmail, Outlook, SendGrid) and differentiates from sibling tools like smtp_check (which tests) and imap_finder (which finds IMAP settings).
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?
Explicitly states 'Use this to find the correct SMTP configuration' and provides examples of providers, giving clear context for when to use the tool. However, it does not mention when not to use it or alternatives such as smtp_check for testing SMTP connectivity.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Each tool has a specific purpose, but dns_lookup overlaps with cname/mx/ptr/txt lookups since it returns all record types. The 'check' tools validate records while 'lookup' tools merely retrieve them, which helps differentiate, but an agent could still confuse e.g., txt_lookup with dkim_check.
Naming follows a noun_action pattern (e.g., bimi_check, mx_lookup) but uses inconsistent actions: check, lookup, finder, and generate. 'imap_finder' and 'smtp_finder' break the noun_verb pattern, and there is no uniform verb choice.
With 16 tools, the count is at the upper edge of reasonable for an email deliverability domain. The individual DNS checks and server tests are justified, but some consolidation (e.g., a single lookup tool with record type parameter) could reduce redundancy.
Covers critical authentication checks (SPF, DKIM, DMARC, BIMI), blacklist checks, DNS lookups, and SMTP/IMAP connection tests. Missing DKIM generation and deeper reputation tools, but core deliverability verification is well-covered.