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

readOnlyHint=true already declares the safe read profile, and the schema's limit description already discloses the no-pagination/truncation behavior. The description adds only the Paymo endpoint mapping (GET /api/projects) and the returned field list, so it clears the lower bar set by annotations but adds little behavioral depth.

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?

Two tight sentences: the capability and returned-field list lead, the endpoint mapping trails. No filler or redundancy.

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 enumerates the returned fields, and annotations cover the read-only profile while the schema covers filtering and truncation. Only a partial field list is given and usage routing is absent, so it is not fully complete.

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 all eight parameters (limit, where, active, include, user_id, billable, client_id, manager_id) are already fully documented in the schema. The description names returned fields rather than filter parameters and adds no interpretation beyond the schema, so the baseline 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?

States a specific verb+resource (list projects) and enumerates the returned fields, so its purpose is unambiguous next to paymo_get_project. It stops short of naming siblings explicitly, so sibling differentiation is only implicit via the list-vs-get naming.

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?

The only guidance is 'optionally filtered,' which restates the schema rather than telling the agent when to choose this tool over paymo_get_project or paymo_list_tasks. No prerequisites, no exclusions, no alternatives are offered.

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