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

Annotations already declare the safe read-only, idempotent, non-destructive profile, so the bar is lower, yet the description still adds substantial behavioral context: the is_group marker and conversation_id for groups, the best-effort caveat that a missing name may appear in message content, and the case/accent-insensitive partial matching. It stops short of describing pagination or result limits.

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 front-loaded with the primary action, but it is a single run-on block that packs lookup modes, group handling, link fields, and best-effort caveats into dense clauses. It is not padded, but the wall-of-text structure reduces scannability.

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 and only two parameters, the description carries the disclosure burden and does so well, covering the shape of results (link, link_readable, is_group) and match semantics. Only pagination/result-count behavior is left unaddressed, which is a minor gap for a read 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 coverage is 100%, so baseline is 3, but the description adds real meaning beyond the schema: it clarifies that `handle` may be a @pseudo, phone number, or display name, that matching is partial and accent/case-insensitive, and that omitting `channel` searches all channels. That is genuine semantic value on top of the structured fields.

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 and resource (retrieve one or more contacts by channel identifier or display name) and enumerates the distinct lookup modes, including group conversations. It is far more specific than a tautology, but it never names a sibling (ficiel_get_lead, ficiel_search, ficiel_get_lead_context) to disambiguate which one an agent should pick.

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 implied rather than stated: the description explains that omitting `channel` searches all channels and that partial/name lookups are accepted, which hints at when to reach for this tool. However, it gives no explicit when-not or 'use X instead' routing against the many lead-lookup siblings, so an agent must infer the boundary.

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