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

Annotations already declare readOnly, idempotent, non-destructive and closed-world behavior, so the bar is lower. The description still adds non-obvious context that annotations cannot express: 'Reads no indexed content and bills nothing' tells the agent there is no cost or side effect to fetching the reference, and it lists the kinds of content the reference contains (arguments, id rules, errors). It does not say how the reference is returned (single text blob, truncated, paginated), which is the one remaining behavioral gap.

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 billing/no-content sentence and the docs link are well placed at the end, and the purpose is front-loaded. However, the opening is a single sprawling colon-and-parenthetical construction with comma-spliced fragments, and the title ('YouTube research reference') is effectively restated. It could be split into two clean sentences without losing content.

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 two-optional-parameter documentation lookup with no output schema, the description covers what the reference contains, how to narrow it, that it reads no content, and that it is free, with a docs URL for depth. Missing only the shape of the response (a single prose document) and guidance that omitting 'topic' returns a very large payload, which the schema rather than the description carries.

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 both parameters are already documented, and the description's 'topic narrows it, like transcript, search, sponsors or monitors' largely duplicates the schema's own example list. The 'intent' parameter is not mentioned at all in the description. Baseline 3 is appropriate when the schema does the heavy lifting.

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 resource ('the reference for YouTube and podcast transcript research in Arcmira') and enumerates what it covers: client methods such as search, transcript, mentions, sponsors and monitors, plus arguments, return fields, id rules, examples and errors. It also distinguishes itself from the sibling that consumes the reference ('the arcmira client methods that arcmira_execute_read programs call'). The phrasing is dense and reads partly as a description of what execute_read can do rather than what this tool returns, which slightly blurs the line.

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?

Usage is implied rather than stated: by describing itself as the reference for methods that arcmira_execute_read calls, the agent can infer it should consult this before executing a read. 'topic narrows it, like transcript, search, sponsors or monitors' gives a concrete narrowing cue. There is no explicit 'call this first', no when-not guidance, and no direct comparison to arcmira_execute_write or arcmira_feedback.

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