list_sources

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

No annotations are provided, so the description carries the behavioral disclosure burden. It reveals a meaningful behavioral trait: summaries are derived from the file's own head (frontmatter description, title plus first sentence, or module docstring), and it exposes the status dimension (found/missing). It does not explicitly state that listing is read-only, but 'List' strongly implies a non-mutating operation.

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 with no filler. It front-loads the core action and output, packs the summary-composition rule into a parenthetical, and ends with a clear directive for downstream use. 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?

Given there are no parameters and no output schema, the description fully covers what an agent needs: the scope ('all knowledge sources indexed by ContextEngine'), the exact fields returned (one-line summary, status, chunk counts), the summary heuristic, and the recommended next step. Nothing essential is missing for a listing 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?

The tool has zero parameters, so there is nothing the description needs to add about parameter meaning. The baseline for zero-parameter tools is 4, and the description appropriately focuses on output rather than inventing parameter details.

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 states a specific verb and resource: 'List all knowledge sources indexed by ContextEngine.' It also details the output contents (one-line summary, status, chunk counts), making the tool's purpose concrete and immediately distinguishable from the sibling read_source, which presumably retrieves a single 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 gives clear usage context: 'Read the summary to pick the right source before calling read_source.' This effectively tells an agent when to use list_sources as a precursor to read_source. It does not explicitly cover when not to use it or mention other alternatives such as search_context, so it stops short of a 5.

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