favicon_fingerprintFetches a same-scope favicon and returns hashes and metadata, never image bytes, to fingerprint web assets during security testing.
Fetch a discovered or conventional same-scope favicon and return stable hashes and metadata, never image bytes.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | ||
| found | Yes | ||
| attempts | Yes |
Changes observed during successful MCP inspections.
v2.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare read-only, idempotent, non-destructive, open-world, so the safety profile is covered. The description adds real behavioral value on top: the fetch is constrained to the same scope, and the response deliberately contains derived hashes and metadata rather than image bytes, which tells the agent how to treat the result.
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?
A single compact sentence that front-loads the action and ends with the constraint that matters most (no image bytes). No filler, no restatement of the name or title.
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 values need not be spelled out, and annotations cover the safety profile. The definition is nearly complete for a one-parameter read tool; only the expected form of 'url' and the behavior when no same-scope favicon is found remain unspecified.
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?
One parameter with 0% schema description coverage, so the description has to carry the load. It hints at input semantics by saying 'discovered or conventional', suggesting the tool will fall back to well-known favicon locations, but it never says whether 'url' is the page URL or the direct favicon file URL, leaving the most important ambiguity unresolved.
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 (fetch/fingerprint) plus resource (favicon) plus scope (same-scope) and a stated output shape (stable hashes and metadata, never image bytes). Nothing else in the sibling list fingerprints favicons, so confusion is unlikely, though no sibling is named or contrasted explicitly.
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?
'Discovered or conventional' implies the two cases in which it is used (a URL already found on a page, or a conventional path), which is useful context. But it never states when to prefer this over technology_fingerprint or web_metadata_discovery, nor any preconditions or failure behavior.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.