fetch_url

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

Annotations already declare readOnlyHint=true, so the agent knows this is safe. The description adds that it returns markdown and can handle pagination with start_index. It does not contradict annotations. Some behavioral details like ignore_robots_txt implications are not explained, but overall adequate.

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 two sentences, front-loaded with the core function, and contains no fluff. 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?

With 5 parameters, an output schema, and 0% schema description coverage, the description is too brief. It fails to explain most parameters (raw, max_length, ignore_robots_txt) and does not mention output format or behavior beyond chunking. The agent would need to infer or experiment.

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 must compensate. Only start_index is mentioned (for chunking). Other parameters (raw, max_length, ignore_robots_txt) are not explained, leaving the agent uncertain about their effects. This is a significant gap for a 5-parameter tool.

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 the verb (Fetch), the resource (public HTTP/HTTPS URL), and the output (page content as markdown). It also mentions chunking with start_index, distinguishing it from siblings like summarize_url or batch_fetch.

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 provides guidance on using start_index for long pages. However, it does not explicitly tell when not to use this tool versus alternatives like batch_fetch or summarize_url, nor does it mention any prerequisites or limitations.

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