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

With no annotations, the description carries the full behavioral burden; it does add useful context by restricting comparisons to hard-metric trends and naming heat/selection score. However, it does not disclose constraints such as minimum entity count, window handling, or side-effect/read-only assumptions beyond what 'compare' implies; the output schema covers return shape.

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 one compact, front-loaded sentence with no filler. The parenthetical defining 'hard-metric' adds relevant meaning without bloating the text.

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 tool with only two simple parameters and an output schema, this is close to minimally usable, but the agent must infer window formats and the relationship to singular/alternative trend tools. The output schema reduces the need to explain return values, but the description still lacks enough surrounding context to be fully self-sufficient.

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 description coverage is 0%, but the description partially compensates by indicating that the 'entities' parameter consists of the things being compared and that the metrics are heat/selection score. The 'window' parameter is left entirely to inference from its name and default value of '30d', so the compensation is incomplete.

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 names a specific action ('compare'), a resource ('hard-metric trends'), and a scope ('across entities'), and it clarifies the metrics being compared (heat / selection score). It does not explicitly distinguish itself from siblings like get_entity_trend or compare_model_costs, so it stops short of a 5.

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?

'Across entities' implies this is the tool for multi-entity comparisons, and the sibling get_entity_trend offers a likely singular alternative, but the description never spells out when to choose this tool over those alternatives or states any exclusions. The guidance is present only by implication.

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