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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. With no output schema, the description usefully discloses the return contents (hours, entry count, billable amount, per-day breakdown), though it says nothing about behavior for a non-matching or ambiguous client name.

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 that names the scope first and the returned metrics second, with no filler.

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 one-parameter read tool with rich annotations, the definition covers scope and output contents, the latter compensating for the missing output schema. It is only slightly short of complete because it omits how ambiguous or non-matching client names are handled.

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% and the single parameter is fully documented, including the partial-name resolution rule. The description merely echoes 'client/project' without adding format or matching detail 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 and resource ('All-time totals for one client/project') plus the exact metrics returned, and the 'All-time' scope implicitly contrasts with the sibling summary_day and summary_week tools. It does not explicitly name those siblings, so an agent must infer the scoping distinction.

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 'all-time' framing implies when this is preferable to the day/week summaries, but there is no explicit when-to-use statement, no exclusion, and no named alternative. Usage is inferable rather than stated.

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