income_by_source

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

With no annotations, the description must carry the burden of behavioral disclosure. It mentions grouping by source, which implies aggregation, but does not state whether the operation is read-only, how month is interpreted, or what the output structure looks like.

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 a single concise phrase with no redundant words, making it easy to parse and front-loaded with the core concept. It is short but not overlong; it sacrifices completeness rather than adding 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 description is too sparse for reliable invocation: it lacks month format, default behavior, return type, and differentiation among many similar sibling reporting tools. The absence of an output schema makes this gap more significant.

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 schema has one optional 'month' field with no description (0% coverage). The description mentions 'for a month' but fails to specify the expected date format, whether omitting month returns all data, or any constraints on the value.

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 clearly states that the tool provides income data grouped by source for a month, which is a specific resource and scope. However, it uses no action verb and does not explicitly distinguish this from sibling tools like income_transactions or get_category_breakdown.

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?

There is no guidance on when to use this tool versus alternatives. The description does not mention use cases, prerequisites, exclusions, or refer to any sibling tool.

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