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

Annotations already establish read-only, idempotent, non-destructive, closed-world behavior, but the description adds valuable context beyond them: it discloses the $0.01 per-call cost, that failed calls are not charged, and the kinds of fields returned. It still does not explain response shape or failure modes in detail, so it is strong but not exhaustive.

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 key retrieval action and then lists the returned fields. Every clause earns its place by adding either context or output expectations.

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 a good job summarizing the deal's return contents, and it covers billing behavior. It could be slightly more complete by specifying the response envelope or error behavior, but for a one-parameter read tool with full annotation coverage it is substantially complete.

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 100% and the single 'deal' parameter is already documented with its origin and an example (eu_oj:M.12591). The description reinforces that the ID comes from mergers_search but adds no meaningful syntax or format guidance beyond the schema, so the 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 states a specific resource retrieval: one deal by an ID produced by mergers_search. It enumerates what the deal record includes (parties and roles, dates, status, value with quoted sentence, source/license), which clearly distinguishes this detail lookup from the search sibling.

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?

It explicitly ties usage to a prior mergers_search result ('the id mergers_search gave it'), giving the agent a clear prerequisite and alternative path. It does not say when not to use the tool or name other siblings such as mergers_acquirers, so it stops short of full when/when-not guidance.

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