project_duration_stats

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

With no annotations, the description carries full burden. It discloses that results are citywide by default and per-group with group_by, but does not mention behaviors like error handling when milestones are missing, read-only nature (implied but not stated), or limits on data volume. It is adequate but not thorough.

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 description is two sentences long, front-loading the core purpose and adding the optional parameter in the second sentence. No redundant words or restatements of the name. Highly efficient.

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?

Given no output schema and many sibling tools, the description lacks detail on the return format (e.g., is it a list of durations, statistical summary?). It also does not cover edge cases like invalid milestone names or from_milestone after to_milestone. It is sufficient for simple use but incomplete for complex scenarios.

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 0%, so the description must compensate. It explains the group_by parameter with explicit values and implies from_milestone and to_milestone are actual milestones needed in pairs. However, it does not define what 'actual' means or provide examples for milestone string values, leaving some ambiguity.

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 clearly states the tool computes duration distribution between two actual milestones, specifying it requires both dates. It distinguishes from sibling tools like delay_reason_stats and schedule_breakdown by focusing on distribution between milestones rather than reasons or timeline views. However, it could be more specific about what 'distribution' means (e.g., histogram, percentiles).

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 description provides some guidance: it requires both dates and explains the optional group_by parameter with allowed values. It does not, however, mention when not to use this tool or suggest alternatives among the 16 siblings, nor does it clarify prerequisites like milestone existence.

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