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

Annotations only cover the safety profile (readOnly, idempotent, non-destructive, closed-world). The description adds genuinely new behavior: long content is paginated, video metadata is not a reviewed transcript, and retrieved text is untrusted reference material rather than agent instructions — a prompt-injection warning that annotations cannot express. The 'never fetches caller URLs' clause is consistent with openWorldHint=false.

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 short sentences, front-loaded with the core purpose, then the video caveat, pagination, and trust model. Every sentence adds distinct, actionable information with no restatement of the name or annotations.

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?

An output schema exists, so return-value explanation is unnecessary, and annotations carry the safety profile. The trust model and pagination are covered, but the id/uri relationship and pagination parameter units remain undocumented for a tool whose schema is 0% described.

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% across four parameters, so the description must compensate. It gives the addressing alternative (id or uri) and implies pagination controls (offset/max_chars) via 'Long content is paginated', but does not state that id and uri are mutually exclusive, nor what units offset/max_chars use. Partial compensation, not full.

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 gives a specific verb (fetch) plus the resource types (published article, video metadata, canonical resource) and the addressing mode (stable id or uri), which implicitly contrasts with the sibling 'search' that must discover identity first. It does not explicitly name a sibling tool, so it stops short of the top score.

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 by 'by stable id or uri' (you must already know the identifier) and a negative constraint ('caller-supplied URLs are never fetched'), but there is no explicit when-to-use/when-not guidance or named alternative such as 'search'. The agent must infer that this is the retrieval step after discovery.

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