onion_lookup

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

With no annotations provided, the description carries the full burden. It discloses a read-only lookup and enumerates the metadata fields returned, but it does not mention input validation, error cases, or the historical nature of the data. This adds some context but lacks deeper behavioral details.

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 sentence, front-loaded with the verb 'Look up', and lists return fields economically. Every word earns its place; no redundancy or 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?

For a simple tool with one parameter and no output schema, the description covers the essential aspects: what it does, the project it queries, and the data returned. It lacks a few details such as result formatting or edge cases, but given the low complexity, it is largely complete.

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 100%: the sole parameter 'address' is already documented as accepting '.onion address or full URL'. The description adds no extra parameter semantics beyond restating '.onion address', so it meets the baseline for high coverage but does not exceed it.

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 clearly states a specific action ('Look up metadata') and resource ('.onion address via CIRCL AIL project'). The listed return fields (first/last seen, status, tags, certificates, ports, Bitcoin addresses) clarify the tool's unique role compared to siblings like tor_fetch_onion or tor_search_onion, which focus on content fetching or searching.

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 implies usage when metadata for a .onion address is needed, but it does not explicitly state when to prefer this tool over alternatives or mention exclusions. No named alternative tools are provided, so guidance is only inferred from the word 'metadata'.

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