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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, and openWorldHint=false, so the safety and idempotency profile is covered structurally. The description adds the required OAuth scope, which is genuinely useful context not present in annotations. It does not, however, explain non-idempotent duplicate-creation behavior or defaults for optional fields.

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 short sentences with the purpose front-loaded and zero filler. The scope requirement is placed second, which is sensible, though the definition is minimal enough that it could have afforded one more sentence of substantive context without becoming bloated.

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?

No output schema exists, so return values need not be described, and the schema fully covers parameters. What is missing is any mention of default status values, what happens on duplicate names, or how the new milestone relates to the parent project - modest but real gaps for a create tool in a large CRUD surface.

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% (all six properties documented, required ones marked), so the schema carries the parameter burden. The description adds no syntax, format, or default-value guidance beyond what the schema already provides, making 3 the correct baseline.

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 states a specific verb and resource ('Create a new project milestone'), which is unambiguous on its own. However, with hundreds of sibling create_* tools including create_project_task, create_project_phase, and create_project_risk, it offers no differentiation or scoping detail beyond the name. Clear but not distinguishing.

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 given is the required scope (project_milestones:write). There is no statement of when to use this tool versus alternatives such as create_project_task or update_project_milestone, and no prerequisites or preconditions beyond the scope requirement.

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