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

Annotations already cover the read-only/idempotent safety profile, but the description adds substantial context beyond them: the currency-conversion condition for billable-rate orgs, the exact null-behavior of CPI/CV/EAC/ETC/VAC when no actual cost is recorded, the actualCostRecorded=false flag, and the instruction to report those as N/A rather than 'on budget'. It also discloses authorization and plan-gate requirements.

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?

Front-loaded with purpose and scope, then progressively less critical detail (return fields, null semantics, routing preference, access, plan gate). Dense but every sentence carries operational information; the null-handling and routing clauses are somewhat compressed into long multi-clause sentences.

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, but the description enumerates the returned metrics and, importantly, explains the null/flag semantics that would otherwise be misinterpreted. Combined with the access rules and plan gate, an agent has everything needed to call it correctly and interpret the result.

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 coverage is 50% — asOf is documented ('ISO date; defaults to now.') while projectId has no schema description. The description confirms asOf's default and scopes projectId to a single project, which partially compensates, but adds no format or constraint detail for projectId. Baseline 3 for a partially covered schema.

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+scope: 'Earned Value Management report for one project as of a given date'. It enumerates the returned metrics (BAC, EV, PV, AC, CPI, SPI, EAC, ETC) and explicitly distinguishes itself from the sibling calculate_evm_history, so an agent can disambiguate without opening a schema.

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 alternative and the condition that selects it: 'PREFER `calculate_evm_history` for time-series'. It also states the access prerequisites (org OWNER/ADMIN or budget.read at project role) and the aiAdvanced plan gate, so an agent knows both when to route elsewhere and whether the caller can invoke it at all.

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