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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds the inline-embedding behavior and the endpoint mapping, but says nothing about failure modes (e.g. nonexistent id) or permission requirements, so it is adequate rather than rich.

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?

A single front-loaded sentence conveys purpose, the optional include capability, and a concrete example, followed by a brief endpoint mapping. No wasted words.

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 two-parameter read tool with no output schema, the description covers the essential purpose and the one non-obvious parameter behavior. The gap is the absence of any hint about the returned object's shape, though annotations remove the need to explain mutability.

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 both project_id and include are already documented in the schema. The description's example of embedding 'the whole task tree' via dotted include paths adds some semantic depth beyond the schema's short example, but the baseline of 3 applies when the schema does the heavy lifting.

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 (Fetch) and resource (one project) with clear singular scope, which naturally distinguishes it from the plural paymo_list_projects sibling. Also names the underlying Paymo endpoint, removing any ambiguity about which entity is targeted.

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 by explaining when to use the include parameter ('include=tasklists.tasks for the whole task tree or include=client'), which is the main usage decision for this tool. It does not, however, state exclusions or explicitly contrast with paymo_list_projects, so it falls short of a full when/when-not routing statement.

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