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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds real value beyond them by disclosing the return shape (budgeted/spent/remaining per budget) and enforcing a month format, which matters since no output schema exists.

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?

Three sentences, each load-bearing: capability and payload, then routing guidance, then the parameter constraint. Front-loaded and free of 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?

For a single-parameter read tool with no output schema, the description covers purpose, when to use it, the argument format, and the returned fields. Only minor gaps remain, such as what happens when no budgets exist for a month.

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 0%, so the description must carry the parameter meaning, and it does: 'Month must be YYYY-MM.' It clarifies the single required parameter's accepted format beyond the raw regex pattern in the schema. It stops short of noting behavior for invalid or omitted months.

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 ('Get the user's budgets') and further specifies the scope ('for a specific month') and payload ('budgeted/spent/remaining for each'). This clearly distinguishes it from the write-oriented siblings like propose_budget_upsert and propose_delete_budget without needing the schema.

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?

Gives explicit usage context: 'Use for questions about budget status, overspending, or remaining budget balances.' It does not name an alternative tool or state exclusions, but the read/write split against the propose_* siblings is unambiguous from the stated intent.

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