search_contacts

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

With no annotations, the description carries the full burden. It discloses the matching behavior via 'fragment', implying partial/substring matching, but it does not state whether the operation is read-only, what output shape to expect, or any limits. For a simple search tool, this is adequate but not rich.

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?

One short sentence, no filler, and the key scoping information ('name or phone fragment') is front-loaded. Every word earns its place.

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 search tool with no output schema or annotations, the description is largely complete: it names the tool's purpose and the query semantics. It could add a note about output or explicitly distinguish from search_messages, but nothing critical is missing for invoking it 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 has 0% description coverage, so the description must compensate. It does by clarifying that 'query' accepts a name or phone fragment, giving the agent concrete guidance on what to pass. This is valuable for a single parameter tool, though it doesn't mention possible exact-match formats or additional accepted values.

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?

Description states a specific verb ('Find') and resource ('contacts') plus a clear scope ('by name or phone fragment'). This distinguishes it from sibling tools like search_messages and list_chats immediately, without needing to inspect schemas.

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 implies usage: when you need to find a contact by name or phone fragment. However, it does not explicitly route away from alternatives such as search_messages, nor does it state when not to use this tool. The guidance is inferred from the resource name and phrasing rather than stated.

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