compare_sources

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

With no annotations, the description carries the burden, and 'compare' at least implies a non-mutating read operation. However, it says nothing about whether the run must have completed collection, whether missing sources are skipped, or any cost/latency behavior, so key behavioral context is absent.

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?

A single front-loaded sentence that names the action, the metrics, and the scope with zero 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?

The tool is low-complexity (one required parameter, read-only aggregation) and an output schema exists, so return values need not be described. The description adequately covers what is compared; only preconditions about the run's state are missing.

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?

There is a single parameter (run_id) with 0% schema description coverage, so the description must compensate. 'Across sources for a research run' gives the parameter meaning by identifying it as the run whose sources are compared, but adds no format or validity detail.

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 (compare) plus the exact dimensions compared (document volume, author count, cost breakdown) and the scope (across sources for a research run). This enumeration also distinguishes it from sibling comparison tools like compare_evidence, compare_audiences, and compare_needs.

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 phrase 'for a research run' implies context but there is no explicit when-to-use guidance, no prerequisites, and no routing to or away from sibling compare_* tools. An agent must infer the scenario on its own.

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