fetch_url

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

With no annotations, the description carries the full behavioral burdenmax and does a solid job: it discloses SSRF protections, redirect revalidation, content-type checks, byte limits, and secret masking. It stops short of describing exact outcomes on failure or blocked content, but the major safety behaviors are transparent.

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 three sentences with no filler. The first sentence states the core operation, the second explains the separation from read_urlholistic, and the third lists safety constraints plus the allowlist exception. Every sentence earns its place.

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?

The description covers purpose, safety behaviors, configuration implications, and policy restrictions, which is strong for a fetch tool. It is slightly incomplete because max_bytes is never explained in relation to the parameter, and expected failure modes are only implied. Still, the overall context is sufficient for most correct calls.

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%, so the description should compensate for the undocumented parameters. It mentions byte limits in general but never maps that to the max_bytes parameter or explains its default semantics. The URL parameter is only implicitly covered by 'public http(s)' in the purpose clause. This is a meaningful gap for a tool with only two parameters.

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 opens with a specific verb and resource: 'Fetch one public http(s) text document for caller-side research.' It also explicitly distinguishes the tool from BoteX's internal read_url, explaining that the orchestrating agent chooses the URL. This makes the tool's role clear and differentiates it from related helpers.

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 names the alternative (read_url) and explains why fetch_url exists: arbitrary public hosts do not need to be configured in net.allowed_hosts. It also notes the allowlist policy restriction. It does not explicitly list exclusions or say 'use this when X, otherwise use Y,' but the context is clear enough for an agent to decide.

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