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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds real context beyond that: lookups are exact-match only, 10-digit US numbers are normalized to +1XXXXXXXXXX as SlickText stores them, and the underlying GET endpoint is disclosed. It doesn't discuss what a match returns, but the added matching semantics are substantive.

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?

Three tight sentences, each doing distinct work: what it does, how matching works, when to use it, and the endpoint. The usage guidance is front-loaded after the purpose, with no filler.

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 lookup with no output schema, the description covers purpose, matching rules, usage timing and endpoint. The one gap is return shape and pagination behavior (limit/offset/next_offset are documented in the schema but the description never mentions iterating results), which is minor for a finder tool.

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 baseline is 3, but the description adds meaning the schema does not: exact-match (non-fuzzy) semantics and the +1 normalization rule for 10-digit numbers, which directly affects how an agent should format the mobile_number argument.

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?

States a specific verb and resource ('Find contacts') plus the lookup keys ('by mobile number or email address') and the match mode ('exact match'). This cleanly distinguishes it from slicktext_list_contacts and slicktext_get_contact, which the agent can rule out without opening their 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?

'Use it before creating a contact to avoid duplicates' gives an explicit usage context tied to the sibling slicktext_create_contact. It does not state when not to use it (e.g., when you already hold a contact ID, in which case slicktext_get_contact applies), so it stops short of full when/when-not/alternatives coverage.

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