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

Annotations already establish a safe, idempotent, closed-world read, so the description's job is to add context, which it does: it says the results are provider-level free credits/programs, one set per service, and instructs broad input harvesting for coverage. It adds no note on how partial matches or unknown services behave, which keeps it below a 5.

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 sentences, purpose front-loaded before the input-sourcing instruction, with no filler. The awkward mid-sentence line break and the 'For a codebase:' preamble are minor inefficiencies rather than wasted content.

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?

An output schema exists and annotations cover the safety profile, so the description only needs to justify input design — which it does with the file list and the 'every external service' directive. The only residual gap is guidance on when this is the right entry point versus build_credit_stack or search_credits.

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% — services, eligible_as and per_service are each documented in the schema, including example package names. The description only reinforces the services parameter's sourcing ('pass every external service you find') and adds nothing about eligible_as or per_service, 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?

The description states a specific verb and resource — list free credits and programs offered by each service provider for a given codebase stack. That is clearly distinct from a generic search tool, though it never names search_credits or search_offers as the sibling an agent should consider instead.

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?

It gives concrete preconditions for good input ('Read package.json, requirements.txt, pyproject.toml, go.mod, Dockerfiles, Terraform and .env.example first and pass every external service you find'), which is real when-to-use guidance tied to a workflow. It stops short of stating when not to use it or which sibling to pick for a non-codebase lookup.

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