fetch_onion

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

Annotations declare readOnlyHint=false, openWorldHint=true, destructiveHint=false, and the description explains why it isn't read-only ('update the local search index') while adding two things the annotations cannot convey: the Tor transport and the fact that the returned content is untrusted text (a prompt-injection hazard). It stops short of covering failure modes, latency/timeouts, or rate limits for an open-world fetch.

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?

Two sentences, zero filler, with the primary action front-loaded and the side effect and the security caveat following in priority order.

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 shape need not be explained, and the description still flags the one thing an agent must know about the output ('untrusted text'). For a mutating, open-world fetch it omits operational realities such as expected latency, timeouts, or whether the index update is transactional, keeping it just short of full coverage.

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 0% and the single 'url' parameter carries no description, so the description must compensate. 'v3 onion page' does implicitly constrain the input to a v3 .onion address rather than arbitrary or clearnet URLs, but no format example or validation rule is given.

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 and resource ('Read a v3 onion page through Tor') and adds a consequential detail: it also 'update[s] the local search index'. This distinguishes it in spirit from crawl_onion (bulk, presumably) and search_onion (query, no fetch), but it never names those siblings, so the differentiation is left to inference.

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 single-page framing ('a v3 onion page') implies this is the one-off fetch rather than the crawler, which is useful implicit routing. There is no explicit when-to-use/when-not and no named alternative among crawl_onion, search_onion, or search_onion_cache, so the agent must guess at the boundary.

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