echo

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It only states that it checks status and is free, but does not reveal what the call returns (e.g., boolean, text, HTTP codes), whether it makes a network request, or any side effects. This is minimal transparency.

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 that is front-loaded with the action and resource. Every word earns its place; there is no redundancy or filler.

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 simplicity (zero parameters, no output schema), the description is adequate but incomplete. It does not specify what the status response looks like or any potential error conditions. Since there is no output schema, the agent must rely on the description to understand the return value, which 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?

There are zero parameters, so the baseline is 4. The description does not need to add parameter information, and it correctly omits any. The schema has no properties, so there is nothing to clarify.

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 states a specific verb 'Check' and a specific resource 'ECHO voice API status', and adds the cost note 'free'. It distinguishes from siblings (which are about key, order, TTS, and voices) by focusing on status. No 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 usage as a status check but does not explicitly state when to use it versus alternatives, nor any exclusions. For a simple zero-parameter tool, the purpose is self-evident, but there is no explicit guidance on when not to use it or what other tools would be better suited.

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 present, so the description carries the full burden of explaining behavior. It only states the action and precondition, but does not disclose whether collection is idempotent, what happens if the order is unpaid, whether the key is returned, or whether the key becomes invalid after collection. This is a significant transparency gap for a non-annotated 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 sentence with no filler, and the primary action is front-loaded. It earns its place, though the brevity contributes to under-specification in behavioral and parameter detail.

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 one-parameter tool, the description gives the essential trigger condition and identifies the relevant parameter, making it minimally viable. However, with no output schema or annotations, it does not describe what the tool returns or what success/failure looks like, so completeness is only partial.

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%, so the description must compensate. It implies that order_id identifies the order whose API key should be collected, but it does not explain where to obtain it, its format, or how it relates to the settled status. The parameter name is self-explanatory, but the description adds minimal semantic value beyond that.

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 names a specific operation ('collect your ECHO API key') and a precondition ('after paying (status=settled)'), which clearly identifies what the tool does. It distinguishes itself from siblings like echo_order by focusing on key collection rather than ordering or voice generation, though it does not explicitly name an alternative.

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 explicitly states when to use the tool: after payment and only when status is settled. This is a clear usage condition, though it does not mention alternatives or when not to use it.

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 provided, the description carries the disclosure burden. It does reveal the mutating nature ('Create') and the expected result (BTCPay checkout URL), which is useful. However, it does not disclose payment order lifetime, expiry, idempotency, or whether funds are captured immediately.

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 sentence communicates action, resource, and output with no filler. The most important information is front-loaded.

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 with one optional integer parameter and no output schema, this description captures the core call model: create an order, receive a BTCPay checkout URL. It is slightly thin on response details and edge cases, but the low complexity means nothing essential is missing for invoking it.

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?

Despite 0% schema description coverage, the description connects 'credits' to 'ECHO credits', giving the single optional parameter some semantic context. It does not explain the default of 50, min/max values, or how credits map to payment amounts, relying mostly on the schema's type/default.

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 ('Create') and a specific resource ('a payment order for ECHO credits'), and the parenthetical 'BTCPay checkout URL' makes the output concrete. This clearly differentiates echo_order from siblings such as echo_tts and echo_voices, which are about text-to-speech and voice listing, not payments.

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 'for ECHO credits' implies the tool is used when a user needs to generate a payment/checkout flow to acquire credits, but the description does not explicitly state when to choose this over alternatives or mention prerequisites. There are no exclusions or alternative-tool references.

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 burden. It usefully discloses that the call costs 1 credit and returns base64 MP3 audio. However, it does not address authentication via api_key, input length limits, or possible error behavior, leaving important behavioral gaps.

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 two short sentences: the first front-loads the action and cost, the second gives the return format. Every phrase earns its place with no 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?

For a simple 3-parameter tool, this is minimally viable: the required text parameter is obvious, the output format is stated, and the cost is disclosed. However, the lack of usage guidance, voice/api_key semantics, and any reference to echo_voices for voice discovery leaves clear gaps.

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%, and the description only clarifies the text parameter ('from text'). It does not explain voice choices, the role of api_key, or how the defaults behave, leaving two of three parameters underspecified.

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 states a specific action and resource: 'Synthesize speech from text' and specifies the output as base64 MP3 audio. This is clear, but it does not explicitly distinguish the tool from siblings like echo_voices or echo_order, so it falls short of a full 5.

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 guidance on when to use this tool versus siblings, nor any exclusions or prerequisites. The '1 credit' note hints at a cost trade-off, but it does not provide actionable selection guidance.

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 provided, the description carries the full burden of behavioral disclosure. 'List' implies a read-only operation, which is a useful safety signal, but the description does not reveal what exactly is returned (e.g., voice IDs, names, metadata) or whether 'available' depends on context. It is minimally transparent but not misleading.

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 is necessary, and it conveys the complete purpose efficiently.

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 listing tool with no output schema, the description is almost sufficient. It states the action and the resource. The only minor gap is not specifying the exact format or granularity of the returned voice list, but given the simplicity of the tool, this is a minor omission.

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 0 parameters, so there are no parameter semantics to clarify beyond the empty schema. Per the rubric, a zero-parameter tool receives a baseline 4, and the description adds no conflicting or unnecessary parameter info. Nothing more is needed.

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 'List available TTS voices' states a specific verb ('List') and a precise resource ('available TTS voices'). It is clearly distinct from sibling tools like echo_tts, echo_beacon, or echo_order, which are different operations entirely, so an agent can immediately identify its purpose.

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 tool's use case is implied by its name and description: if an agent needs to discover which TTS voices exist, this is the tool. However, it gives no explicit guidance about when to prefer it over alternatives (e.g., whether it should be called before echo_tts) and no exclusions. The context is clear by itself but not stated.

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