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

Beyond the readOnly/idempotent/openWorld annotations, it discloses the windowing contract in detail: each result holds the lines from start that fit in one reply, next_start is the value to pass for the next window and is null after the last line, and continuation is guaranteed gap-free and without repeated lines. It also states the payload shape (timestamped lines, speaker when known, title, channel, publish date, length).

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?

Front-loaded with purpose, then when-to-use, then the pagination mechanism — a sensible order. The opening sentence is long and clause-heavy, but every clause carries information an agent would otherwise have to guess.

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?

There is no output schema, and the description fully compensates by describing the returned fields and the next_start pagination state. For a mutation-free read tool with four well-documented parameters, nothing an agent needs to call it correctly 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%, so baseline is 3, but the description adds genuine semantics: start 'also opens the transcript at a given second', next_start is what to feed back as start, and language selects caption language. It does not elaborate on the intent or video-id format beyond the schema, keeping it above baseline rather than maximal.

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?

Specific verb plus resource: 'Reads the whole transcript of one YouTube video, podcasts on YouTube included, from its id or any youtube.com or youtu.be link,' followed by exactly what comes back. An agent can distinguish this from arcmira_youtube_search (find videos) and arcmira_execute_read (generic read) 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 trigger conditions are given: the user shares a youtube.com/youtu.be link to summarize, quote or check, or asks what a video or podcast said. It does not name a sibling as the alternative path (e.g. youtube_search when only a title is known), so the routing is clear but not fully exhaustive.

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