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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world scope, so safety is covered. The description adds real behavioral context beyond that: what last_event_at means, that it can be null, and how a stale value should be interpreted ('an old one on a busy account can mean it went quiet'), plus the 'No provider ids' limitation. It does not mention default/maximum page size or ordering guarantees.

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?

Front-loaded with the resource and return fields, then filters, then the interpretive note on last_event_at. Every clause carries information — the parentheticals are dense but each one answers a question the schema leaves open. No filler sentences.

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, the description correctly supplies the returned field list and explains the one non-obvious field. Combined with zero schema coverage on 7 parameters, it covers nearly everything an agent needs to call this correctly. The gap is external_id, which appears in the schema but is neither explained nor reconciled with the 'No provider ids' claim.

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 description carries the load and mostly does: it documents q (name or id), channel, status (comma lists, with the needs_attention pseudo-value), sort (enumerated fields, leading '-' for descending), limit and cursor (from next_cursor). Only external_id is left undocumented, and the closing 'No provider ids' sits in tension with that parameter rather than clarifying it.

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 names the resource precisely and scopes it to connected accounts across five channels, plus enumerates the returned fields (id, channel, name, status, connected_at, status_since, last_event_at). It never uses an explicit verb like 'list', but the resource and scope are unambiguous. Differentiation from get_connected_account is only implicit via the 'Use the id as account_id' line.

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?

Gives concrete usage context: 'Use the id as account_id in the other messaging tools' tells the agent what to do with the results downstream, and the filter/sort/pagination clauses explain how to narrow the listing. It stops short of stating when to pick this over get_connected_account for a single account, and offers no exclusions.

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