Email Server

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

No annotations are provided, so the description carries the full behavioral burden, and it discloses almost nothing: no indication that the operation is read-only and side-effect free, and no hint of what is returned (e.g., a greeting string). The word 'simple' weakly implies triviality but is not a reliable disclosure of behavior.

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 a single short phrase with zero filler and is front-loaded, which suits a trivial one-parameter tool. It is arguably under-specified rather than overly concise, but there is no wasted text.

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 very simple (one required string param, 100% schema coverage, no output schema), so minimal description is defensible. However, with no output schema or annotations, the agent has no information about what greet returns or whether it has side effects, leaving a small but real gap.

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% — the 'name' parameter is documented as 'Name to greet' — so the baseline is 3. The description adds nothing about the parameter (e.g., whether it is a display name, a required greeting target, or how it is rendered), so it neither helps nor hurts beyond the schema.

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 identifies the domain (greeting) but is essentially a restatement of the tool name 'greet' — 'A simple greeting tool' adds almost no specificity about what the tool produces or how it greets. It is not misleading, but it does not distinguish behavior beyond the name, and it gives no differentiation from the sibling send_email.

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?

There is no when-to-use guidance, no prerequisites, and no mention of alternatives such as send_email. The agent is left to infer usage entirely from the name, which is the minimum context for a one-parameter tool but still a clear gap.

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, the description carries the full behavioral burden, yet it only names the backing API. It omits that the sender must be verified in Resend, whether sending is idempotent or reversible, rate limits, and failure behavior for an operation that performs an external side effect.

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 short sentences, front-loaded with the core action, with no filler. The second sentence restates schema-documented fields rather than adding value, which slightly dilutes it but keeps the definition tight.

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 an 11-parameter outbound email tool with no annotations and no output schema, the description is thin. It should disclose the verified-sender requirement, scheduling semantics for scheduled_at, and what a successful send returns, none of which are covered.

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 the schema already documents all 11 parameters including formats and limits (max 50 recipients, 40MB attachments, verified sender). The description's mention of html_content/text_content adds nothing beyond the schema, so the 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 and resource ('Send emails') plus the underlying service ('via Resend API'), which is enough for an agent to know exactly what the tool does. The only sibling is 'greet', an unrelated tool, so no differentiation is needed, but the description also doesn't address scope (e.g., transactional vs bulk).

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?

There is no when-to-use guidance, no prerequisites, and no alternatives are named. The clause 'Provide html_content and/or text_content' hints at a body-requirement constraint but is phrased as an instruction rather than a routing rule, so it provides little selection guidance.

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