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

Annotations already establish read-only, idempotent, non-destructive, closed-world behavior. The description adds useful behavioral context beyond that: rates are 'today's indicative' figures, each figure is 'dated and sourced,' and a head-to-head comparison page is included 'when one 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?

The description is a single dense sentence that front-loads the core comparison action and then lists return details. Every element earns its place, though the packed enumeration makes it slightly less scannable than an ideal front-loaded definition.

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?

With no output schema, the description does most of the work by listing the compared metrics and noting sourcing and comparison-page inclusion. It is complete enough for invocation, though it does not describe output ordering or behavior when fewer comparison dimensions are available.

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 100%, and the schema already documents the programs array, allowed enum values, and min/max items. The description reinforces the 'two or three programs' constraint but adds no slug-level semantics beyond what the schema provides, so baseline 3 is appropriate.

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 compares two or three commercial mortgage programs side by side and enumerates the metrics returned. It does not explicitly distinguish itself from siblings such as match_programs or program_rules, but the verb+resource is clear enough for an agent to identify the tool's role.

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 'Two or three commercial mortgage programs side by side' implies this is for comparing selected programs, but the description gives no explicit when-to-use guidance or alternatives. It never mentions match_programs, get_rates, or program_rules, so the agent must infer the selection context.

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