fetch_llms_txt

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

With no annotations the description carries full burden. It discloses useful traits: it tries two file variants, is faster than fetch_page, and returns curated LLM-oriented content. However, it never states what happens on failure (no llms.txt present) or whether it falls back to fetch_page, which is the key behavioral question for a best-effort fetch.

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?

Four short sentences, front-loaded with the action, then rationale, then routing guidance, then the input constraint. Every sentence earns its place with no padding.

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 single-parameter fetch tool with no output schema and no annotations, the description covers purpose, routing, and input format adequately. The only gap is failure/fallback behavior, which is minor for this simple tool.

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 coverage is 100% and the single parameter is fully documented in the schema. The description's 'Give it a domain, not a full URL' largely restates the schema's own 'Do NOT include https:// or paths' constraint, adding little beyond it. Baseline 3 is appropriate.

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?

States a specific verb (fetch) and resource (llms.txt or llms-full.txt from a domain), and explicitly distinguishes itself from the fetch_page sibling. An agent can tell exactly what this does without opening the schema.

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?

Explicitly says 'Use this INSTEAD of fetch_page for documentation sites' and gives the condition (docs.example.com). Names the alternative and the situation that selects it, leaving nothing to inference.

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