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

Annotations already declare readOnly, idempotent, and non-destructive, but the description goes further: it states that the tool does not use credits and does not start anything, and it discloses that credit balance is not available via the API, directing users to the web app. These are behavioral details beyond what annotations capture, providing real value for an agent deciding whether to call it.

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 short paragraphs, each with a distinct purpose: purpose, when to use, and notes. Every sentence earns its place with no filler. The key purpose is front-loaded, and the caveats are placed last without bloating the 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?

For a zero-parameter health-check tool with no output schema, the description fully covers what an agent needs: what it does, when to use it, what it doesn't affect, and an important limitation (credit balance). The sibling tools are all about renders, so this check tool is clearly distinct. Nothing essential 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?

The tool has zero parameters, so there is nothing to describe. The schema coverage is trivially 100%. Per the baseline rule, a score of 4 is appropriate because the description adds no parameter-specific info, but none is needed. The description correctly avoids inventing unnecessary parameter explanations.

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: 'Verify that this server can reach LipDub and report which account it is using.' This is unambiguous and clearly distinguishes it from the sibling render-management tools. Even without seeing the siblings, the tool's role is immediately understandable.

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 when to call it: 'Call this first if any other LipDub tool fails with an authentication error, or when a user asks whether LipDub is set up.' It also clarifies what it does NOT do (uses credits, starts anything), which prevents misuse. This is textbook usage 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?

Goes well beyond the annotations by disclosing financial consequences ('USES CREDITS', 'cannot be undone or refunded'), cost scaling with source video length, asynchronous behavior (returns render_id immediately, render not finished), and typical render duration. No contradiction with the annotations; this description adds substantial behavioral context.

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 front-loaded with the most critical information (purpose and cost warning), then organized into clear paragraphs and bullet lists covering inputs, exclusions, and post-call behavior. Every sentence earns its place; the length is justified by the tool's high-stakes, asynchronous, and easily-misused nature.

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 no output schema, the description fully explains what the caller should expect: an immediate render_id, that rendering is asynchronous, how long it may take, and the required next step. It also covers prerequisites, URL constraints, known failure modes, and the spending-confirmation gate, making it complete for correct invocation despite the schema listing all parameters as optional.

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?

Even though schema coverage is 100%, the description adds crucial meaning: URLs must be direct, publicly downloadable media files; YouTube links are resolved but Google Drive/Dropbox share pages and login-protected links fail; video must show one person with a clear face; audio must be finished because LipDub does not generate speech. This meaningfully enriches the schema's parameter descriptions.

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 ('Start a LipDub 2 render') and a clear resource with the intended effect: making the person in a source video appear to speak a different audio track with matched lip movement. This clearly distinguishes it from siblings like lipdub_list_renders, lipdub_get_render, and lipdub_wait_for_render, none of which create a render.

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?

Provides explicit when-to-use and when-not-to-use guidance: confirms credits must be approved by the user first, instructs to call again with confirm_spend=true, warns that LipDub 2 does not translate/transcribe/generate speech, and routes follow-up to lipdub_wait_for_render. It also explains when callback_url is appropriate versus chat-session use.

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?

Annotations already cover readOnlyHint and idempotentHint, and the description layers genuinely useful context on top: the immediate-non-waiting behavior, the full status enum with meanings, and the critical caveat that download_url is a temporary signed link that must be handed to the user or downloaded promptly. 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?

The description is front-loaded with the core single-check purpose and the critical non-waiting distinction, followed by usage, rate limits, status enum, and URL handling in logical order. It is slightly verbose — the status enum and expiry caveat could theoretically live in an output schema — but every section earns its place with no 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?

For a one-parameter tool with no output schema, the description covers everything an agent needs: the status value set, what download_url contains and its expiry behavior, how render_id is obtained, and routing to the wait sibling. Nothing required for a correct 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 100% and the schema already documents render_id thoroughly ('The render_id from lipdub_create_render. A plain number is also accepted.'). The description just restates the source ('Takes the render_id from lipdub_create_render'), adding little beyond the schema. Baseline 3 is appropriate since the schema carries the load.

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 precise verb-resource pair — 'Check a LipDub render once, right now' — and distinguishes itself from lipdub_wait_for_render by clarifying what it does NOT do ('does NOT wait'). This makes it trivially distinguishable from its siblings without opening any 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?

Explicit when-to-use and when-not-to-use guidance is given in two places: 'To wait for a render to finish, use lipdub_wait_for_render instead' and the closing 'If the render is not finished yet, prefer lipdub_wait_for_render'. It also states the unthrottled nature ('Free and never rate-limited — check as often as you need'), giving the agent a clear green light for polling.

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?

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds valuable context: it is account-scoped, returns 'a short summary of each', and is 'Free and never rate-limited'. This goes beyond the annotations by disclosing cost and rate-limit behavior, which is genuinely useful for an agent deciding whether to call it.

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 well-structured with a clear main statement, bullet-pointed 'when to use' triggers, and a note about returns and cost. It is slightly longer than strictly necessary, but every section serves a purpose and no sentence is wasted. The main action 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 simple listing tool with one optional parameter and no output schema, the description covers the essential information: what it returns (short summary), how to proceed to get a download link (via lipdub_get_render), and cost/free status. It does not describe the exact shape of the summary, but that is not critical for invoking the tool. Overall it is sufficient for correct usage.

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 single parameter 'limit' is fully documented in the input schema (type, default, min, max, description). The tool description adds no additional semantics beyond the schema — it does not mention pagination limits or default behavior. With 100% schema coverage, the baseline of 3 is appropriate; the description does not need to repeat schema details.

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 verb ('List'), a resource ('LipDub renders'), and a scope ('on this account'), plus an explicit ordering ('newest first'). It clearly distinguishes from siblings like lipdub_get_render (retrieve one) or lipdub_create_render (make new), so an agent can immediately identify the tool's role.

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 provides explicit 'Use this when' conditions: losing a render_id (e.g., after conversation trimming) or when the user asks for recent renders. It also advises the follow-up call to lipdub_get_render, giving clear decision guidance about when this tool is appropriate and what to do next.

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?

Annotations declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint false, but the description adds critical behavioral detail beyond these: the blocking nature, the max_wait_seconds cap, the normal return with still_running, and the explicit statement that it is not an error. 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?

The description is efficiently organized: purpose first, then usage, then behavior, then user guidance. Every sentence earns its place—no fluff. It front-loads the core purpose and the key differentiator, and the length is appropriate for the complexity of the tool.

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?

Despite lacking an output schema, the description fully covers what an agent needs: how to call it, what to expect (including partial results), how to handle still_running, and cost/rate-limit implications. It leaves no gaps for correct invocation and follow-up.

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 100% (both parameters documented). The description adds context beyond the schema, such as explaining that renders take several minutes and it's normal to call repeatedly, which informs how to set max_wait_seconds. However, the schema already covers the key semantics of max_wait_seconds and still_running, so the description's extra value is limited but present.

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 precise verb-resource pair: 'Wait for a LipDub render to finish, then return its download link.' It explicitly differentiates from alternatives by stating to use it 'straight after lipdub_create_render instead of checking in a loop,' making the tool's purpose unambiguous and distinct from siblings.

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 explicit when-to-use guidance: 'Use this straight after lipdub_create_render instead of checking in a loop.' It also instructs what to do when still_running is true: tell the user, provide the render_id, and call again. It even notes that repeated calls are normal and free, covering both timing and cost expectations.

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