YouTube Transcript Downloader

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

Annotations declare readOnlyHint=true and destructiveHint=false, but the description adds substantial non-obvious behaviors: per-video credit charges, repeat calls charged, videos without captions skipped free, API key requirement, and a rate limit of 5 requests per 10 seconds. This goes well beyond the annotation's minimal safety info.

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 purpose, then usage, then cost and rate-limit details. Each of the three sentences carries distinct, necessary information without redundancy or fluff.

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 description covers the purpose, output format, usage context, cost model, API key requirement, rate limit, and free skips. With an output schema present, return values are handled structurally, so this leaves no major gaps for an agent to misuse the tool.

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% for both parameters (url and limit), so the schema already documents their basic meaning. The description adds extra semantics for limit: it acts as an upper bound on credit charge and gives typical cost examples ('A 10-video call typically costs up to 10 credits'), which helps agents select an appropriate value.

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?

Description states a specific verb and resource: 'Get transcripts for a YouTube channel's most recent videos (newest first) as timestamped markdown, one section per video.' It also distinguishes from sibling tools by noting that for a single known video, get_transcript should be used.

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 provides when to use: 'Use for research across a creator's recent output; for one known video use get_transcript.' This names an alternative and gives clear context, fulfilling the guidelines requirement.

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 provide readOnlyHint=true and idempotentHint=false, and the description aligns by saying 'Read-only' and 'including repeat calls' for credit charges. It adds valuable context: API key requirement, per-video credit cost, free skips for videos without captions, and a rate limit.

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?

Four sentences each serve a distinct purpose: purpose/format, usage/alternative, cost behavior, and rate limit. No wasted words, perfectly front-loaded with the core function.

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 description covers selection criteria, invocation constraints (auth, cost, rate limit), output format, and differentiates from siblings. With an output schema present, no further return-value detail is needed.

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%, so baseline is 3. The description adds extra meaning to the 'limit' parameter by framing it as an upper bound on credit charge ('start with a small limit'), which is useful beyond the schema's default/maximum.

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 exactly what the tool does: gets transcripts for videos in a YouTube playlist in playlist order as timestamped markdown. It clearly distinguishes from sibling get_transcript by explicitly directing 'for one known video use get_transcript'.

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 use this tool ('for working through a course, series, or curated list') and provides an alternative for a single video. Also includes practical usage constraints such as credit costs and rate limits.

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?

Beyond annotations, the description adds critical behavioral details: API key requirement, 1-credit cost per call including repeats, advice to reuse transcripts, no cost for videos without captions, and a rate limit of 5 requests per 10 seconds. This enriches the annotation readOnlyHint with concrete operational constraints.

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?

Four sentences, each adding essential value: purpose/output, read-only nature, cost/billing, and rate limiting. Front-loaded with the core action, no fluff or repetition.

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 read-only tool with an output schema, the description covers all necessary behavioral aspects: what it returns, side effects (none destructive), costs, error conditions, and rate limits. Completely sufficient for an agent to invoke confidently.

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 fully describes the single parameter 'video' with details on ID and URL forms (100% coverage). The description adds 'single YouTube video' scope but no additional syntactic or semantic detail, so it meets the baseline without compensating further.

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 ('Get') and resource ('full transcript of a single YouTube video') with an explicit output format ('timestamped markdown'). It clearly differentiates from sibling tools by emphasizing 'single video', unlike channel/playlist transcript tools.

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 clear usage context: read-only, requires API key, charges credits, rate limits, and error behavior. It implies a single-video scope versus siblings, but does not explicitly name alternatives or state when not to use. Solid guidance but not fully explicit about when to choose this over other tools.

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?

Beyond the readOnlyHint annotation, the description discloses credit charging (about 3 per 1,000 words, minimum 5), repeat calls are charged, requires API key, rate limit of 5 requests per 10 seconds, and error cases that do not charge. This is rich 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 a single, well-organized paragraph. Every sentence adds value: purpose, use case, alternative, read-only, credits, errors, and rate limit—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?

Given the tool's complexity, the description explains expected behavior (cleaning), costs, error conditions, and rate limits. With an output schema present, return format is covered, making the description complete for selection and invocation.

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 already fully describes the single 'video' parameter with ID/URL examples (100% coverage). The description adds no additional parameter semantics, so it meets the baseline of 3.

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 'Get a cleaned-up transcript' and details the exact transformations (punctuation, capitalisation, filler removal). It distinguishes itself from sibling get_transcript by noting that it polishes auto-generated captions.

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?

It explicitly states when to use ('Use when raw captions are too messy to read or quote') and directs to an alternative ('for a plain transcript use get_transcript'). It also excludes cases that error out (human-uploaded captions, transcripts over ~7,000 words).

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