fetch

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

With no annotations, the description carries the full behavioral burden. It does well here: discloses the return shape (confidence, method, tier), instructs the agent to check confidence before trusting, and guarantees no silent empty results on failure (failure_reason). This is rich, actionable behavioral context.

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?

Well-structured with a clear one-line summary, then formatted Args section, then return/failure details. Every sentence earns its place — no fluff, front-loaded with the key purpose statement.

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?

Despite having only 2 simple params and an output schema, this is a complex tool (multi-tier escalation). The description covers the fetch strategy, both parameters, the return contract, confidence guidance, and failure semantics. Exceptionally complete for its complexity level.

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?

With 0% schema coverage, the description must compensate fully. It documents both parameters: url (clear from name/schema) and mode, explaining markdown vs raw semantics with clear defaults. The mode explanation adds real value beyond the schema's bare type/default.

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?

Clear verb+resource ("Fetch a URL") with specific mechanism described (resilience ladder with tier escalation). Distinguishes itself from sibling extract tool by being the URL-fetching primitive, and references a distinctive multi-tier strategy.

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?

Describes the escalation behavior (static -> rendered, escalating when failure suggests it helps), giving an agent context on how the tool self-optimizes. Doesn't explicitly name alternatives or say when NOT to use it, but the clear scope of the tool makes this a minor gap.

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