list_sources

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

With no annotations, the description carries the burden of behavioral disclosure. It reveals important behavior: it returns per-source article counts and indicates whether the app uses bundled defaults (feeds.txt empty) or user selection. This goes beyond a bare 'list' statement, though it does not explicitly confirm a read-only side-effect profile.

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?

Two concise sentences, front-loaded with the primary purpose in the first sentence. The second sentence adds meaningful detail without redundancy. Every word 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?

For a zero-parameter read-only listing tool, the description fully covers what is returned (feeds, article counts, default-vs-user status). An output schema exists, so return details need not be fully re-explained. The context is complete for the tool's complexity.

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?

The tool has zero parameters and schema coverage is 100% (empty). With no parameters to describe, a baseline of 4 is appropriate; the description adds no parameter detail but none is needed.

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 opening verb 'List' plus the specific resource 'feeds the digest currently aggregates' clearly states the action and scope. It further specifies what is reported (number of stored articles per source and whether default or user feeds), distinguishing it from sibling tools like add_source/remove_source.

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 implies when to use the tool (when you need to see current aggregated feeds) but does not explicitly mention alternatives or when not to use it. It lacks explicit comparison to siblings like search_archive or get_articles_for_digest, so usage guidance is only implied.

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