Add llms.txt source

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

Annotations already disclose the write, non-idempotent, open-world profile. The description adds real value on top: persistence across restart, the validation rule (must be text with links, not an HTML stub), and that a HEAD request determines the companion llms-full.txt size. That is substantive behavioral context beyond the annotations.

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?

Front-loaded with the core action and the persistence fact, followed by the validation and HEAD details. Three sentences, each carrying information, with no filler.

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 explained. The description covers what happens on add (download, validate, size probe) and points forward to llms_index, leaving little an agent needs before invoking it.

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%, so all three parameters are already documented in the schema, including the index default and the domain format example. The description adds only implicit context about the index address, so the 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 and resource: 'Add a source to the registry', with the concrete artifact (llms.txt) named in the title. An agent can distinguish this from llms_remove_source and llms_list_sources, though the description itself never names those siblings.

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?

Usage is implied by the name and by the trailing pointer that 'other variants are shown later by llms_index', but there is no explicit when-to-use-this-vs-alternatives guidance or stated prerequisites for registering a source.

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