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

With no annotations provided, the description carries the full behavioral burden. It discloses that the operation is a pure computation that returns the sum, implying no side effects. It does not mention edge cases like floating-point precision, but that is acceptable for a simple adder.

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 concise sentence with no wasted words, front-loading the core purpose and result.

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 simple, stateless arithmetic operation, the definition is complete. The input schema defines both required parameters, and the description explains the output behavior ('returns the sum'). No output schema exists, so the explicit return description is necessary and sufficient.

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 has 0% description coverage, so the description must compensate. It states 'two numbers', implicitly clarifying that a and b are the addends, which adds meaning beyond the raw schema. It does not elaborate on individual parameters, but the parameter names are self-explanatory.

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 'adds', names the resource 'two numbers', and states the outcome 'returns the sum'. It clearly distinguishes this tool from unrelated siblings echo and server_time.

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 clearly implies when to use the tool: anytime two numbers need to be summed. It does not explicitly compare with alternatives, but the siblings are unrelated (echo, server_time), so no confusion exists.

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 full burden. 'Echoes the provided text back to the caller' fully discloses the observable behavior and implies no side effects or mutations. There is no hidden state or destructive action to warn about.

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 efficient sentence with no filler. It is immediately clear and every word 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?

For a tool this simple, the description plus schema completely cover what an agent needs: the single required parameter is documented, and the return behavior ('echoes back') is stated. No output schema is necessary because the result is the same text.

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 input schema already documents the 'text' parameter as 'Text to echo back'. The description adds only the word 'provided', so it provides no meaningful semantic value beyond the schema, but the schema fully compensates.

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 ('Echoes') and a clear resource ('the provided text'), stating exactly what the tool does. It is immediately distinguishable from siblings like add and server_time, so an agent can select it without ambiguity.

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 implies the use case through the verb 'echoes', but it does not explicitly state when to prefer this tool over alternatives or mention any exclusions. For a trivial utility this is adequate, though no direct guidance is provided.

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 full burden. It discloses the key behavioral facts: the value is the current server time, formatted as ISO 8601, expressed in UTC. It does not explicitly state that the call has no side effects, but 'returns' and the zero-parameter signature imply read-only behavior sufficiently for this simple 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?

The description is a single, front-loaded sentence with no filler. Every word contributes: the action, the resource, the format, and the timezone are all present without redundancy.

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?

Given the tool's trivial complexity—no parameters, no annotations, no output schema—the description is fully complete. It states what is returned and in what format, which is all an agent needs to call and interpret the result correctly.

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 input schema has zero parameters, so the baseline is 4. There are no parameter semantics to explain, and the description accurately reflects that the tool requires no input.

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 ('Returns') and a clear resource ('current server time'), and adds the exact format and timezone ('ISO 8601, UTC'). This fully differentiates it from the unrelated siblings add and echo, so an agent knows exactly what the tool does.

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?

For a zero-parameter utility, the intended usage is immediately clear: call this tool when the current server time in UTC is needed. There are no overlapping sibling tools and no preconditions to document, so the absence of explicit when-not-to-use guidance is not a meaningful gap.

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