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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so safety is covered. The description adds genuine behavioral context by spelling out what the response contains (members plus each group's role and own-records-only flag) and warning that it should be read before mutating visibility.

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 core sentence is dense but front-loaded with the verb and resource, and the guidance sentence follows. The parenthetical keyword list ('get portal groups, show client groups') is search-alias padding rather than information, which is the only real cost.

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 usefully compensates by describing the returned structure. For a two-parameter, read-only listing tool with full annotation coverage, nothing essential is missing; pagination and volume characteristics are the only unstated details.

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%, and both parameters (app_id, portal_id) already document their source tools (list_projects, list_portals/describe_project). The description adds no additional parameter meaning, so the baseline of 3 applies.

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?

Names a specific verb and resource ('list a portal's user groups') and then enumerates the payload precisely: members, per-table/report role, and whether the group sees only its own records. An agent can distinguish this from list_portal_users, list_team_groups, and list_user_roles from the description alone.

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 an explicit usage trigger: 'Read it before changing who sees what: the group you need usually exists already.' That is actionable pre-write guidance, though it does not name the alternative tools (create_portal_group, add_user_to_portal_group) it is meant to precede.

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