matrix_list_joined_rooms

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

With no annotations, the description carries the full behavioral burden. It does disclose useful traits: pagination via cursor, the tenant defaulting rule, and the fields returned. It omits any statement about permissions/auth needed to list joined rooms or what happens on invalid tenant.

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?

Short and front-loaded, with the core purpose first and operational notes after. The telegraphic fragments ('Homeserver to target.', 'Cursor-paginated.') are terse but each carries information.

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 simple read-only list tool with an output schema present, the description covers purpose, pagination, and tenant selection. The main gap is the undocumented 'limit' parameter, which is minor given the output schema exists.

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 0%, so the description must compensate. It handles 'tenant' well (what it targets, the default-omit behavior, and the available values) and gestures at 'cursor' through the pagination note, but 'limit' is never explained and cursor's integer-offset semantics are left to the schema.

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 ('List rooms the configured account has joined') and even previews the returned fields (name, topic, encryption flag). It is clearly distinguishable from siblings like matrix_get_room_info or matrix_list_room_members by resource scope, but it never explicitly contrasts itself with them.

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 agent can infer this is the tool for enumerating joined rooms, and 'Cursor-paginated' hints that repeated calls may be needed. There is no explicit when-to-use/when-not guidance or mention of alternative tools such as matrix_search_messages for finding a room.

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