search_contacts

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

With no annotations, the description carries the full behavioral burden, and it does disclose the payload ('returns their phone numbers'), which is genuinely useful given there is no output schema. However, it omits match semantics (substring vs prefix vs fuzzy), result limits or pagination, and whether 'chats' means group chats. The read-only nature can only be inferred from the word 'Search'.

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 sentence, front-loaded with the action and immediately followed by the accepted input types and the returned data. Nothing is redundant or padded.

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 read tool with no annotations and no output schema, the description covers what it searches, on what fields, and what it returns. The remaining gaps (match behavior, result caps, ambiguity handling) are minor for this complexity level.

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%, so the bare 'query' string needs explanation, and the description supplies it: the value may be either a name or a phone number. That is real meaning beyond the schema, though it does not specify partial-match or formatting rules for phone numbers.

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 gives a specific verb and resource ('Search contacts and chats') plus the query modality ('by name or phone number'), which distinguishes it from message-returning siblings such as search_messages and list_chats. It stops short of explicitly naming an alternative, so an agent must infer the boundary from the returned content.

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?

Usage is only implied: the phrase 'returns their phone numbers' suggests the tool is for looking up a contact's number. There is no explicit when-to-use statement, no exclusion against search_messages or list_chats, and no note about what to do when a query matches multiple people.

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