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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower; the description still adds real behavioral context by saying the tool detects infeasibility and reports it explicitly, plus the alternative outputs (max reachable GPA, credits needed at straight A's, longer horizons). It repeats some return-value content that the output schema already declares, so it is slightly redundant rather than maximally additive.

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-loads the trigger condition, then outputs, then exclusions – a sensible order with no filler sentences. The long chained clause listing every return value plus the keyword-style parenthetical ('gpa calculator with current gpa') costs it a point on tightness.

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 5-parameter read-only computation with a full output schema, the description covers trigger, inputs, output scope, infeasibility handling, and sibling boundaries. Nothing needed to call it correctly is missing.

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 100%, including the non-obvious max_gpa scale variation and the 'use 0 for a first term' hint on credits_completed, so the schema carries the load. The description only names the four required inputs in passing without adding format or edge-case semantics beyond what the schema says; 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+resource (compute the GPA required on upcoming credits to hit a target cumulative GPA) and anchors it to the user phrasing that should trigger it. It explicitly separates itself from calculate_gpa, and the subject matter makes it distinguishable from final_grade_needed as well.

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 a concrete when-to-use condition ('user asks what GPA they need next semester to reach a target cumulative GPA') with example phrasings, plus an explicit exclusion routing to calculate_gpa and a statement that admissions-chance judgment is out of scope. When/when-not/alternative are all present.

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