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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context: it returns structured deal data with specific fields (acquirer, target, offer price, total value, premium, acceptance %, status, timeline) and enumerates the deal types included. It does not mention pagination or default limits, but the schema covers the limit parameter. This is solid value beyond annotations without contradicting them.

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 three sentences with zero waste. The core purpose is front-loaded in the first sentence, the return structure in the second, and the usage triggers in the third. Every sentence earns its place, and the structure is easy to scan.

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 read-only, idempotent tool with a 100% schema-covered parameter set and an output schema, the description is nearly complete. It explains what the tool returns, which deal types are covered, and when to use it. The only minor gap is that it doesn't explicitly state the default limit or pagination behavior, but the schema's 'limit' parameter description covers the default, and the output schema handles return values. This is complete enough for an agent to select and invoke correctly.

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%, so the schema already documents all five parameters. The description adds the deal-type taxonomy and the trigger phrases, which enrich understanding of the 'deal_type' and 'status' parameters, but it doesn't add syntax or format details beyond the schema. Baseline 3 is appropriate because the schema carries the heavy lifting and the description provides only marginal extra meaning.

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 verb ('Get'), a clear resource ('M&A and takeover activity for an NZX company'), and enumerates the exact deal types covered (takeover offers, mergers, schemes of arrangement, compulsory acquisitions, asset acquisitions). It also lists the structured fields returned, which distinguishes it from sibling tools like get_capital_raises or get_company_detail. The trigger phrases ('takeovers', 'M&A', 'acquisitions', 'hostile bids') further clarify scope.

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 description provides explicit trigger phrases and a clear context ('when asked about...'), which tells an agent when to select this tool. It does not explicitly name sibling alternatives or state when NOT to use it, but the trigger list plus the deal-type enumeration gives strong usage guidance. A small gap: it doesn't contrast with get_capital_raises or get_company_detail, but the specificity of the trigger phrases largely compensates.

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