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

Annotations declare readOnlyHint=false and idempotentHint=true, and the description explains why: the quote 'binds accepted versions', i.e. it records state rather than being a pure read. It also discloses the credit pricing model (5 credits for a new export, free for existing downloads) and the get_project dependency, which the annotations do not cover.

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?

Tight and front-loaded: the no-spend framing and cost figure come first, then the prerequisite and binding note. The trailing fragment 'Quote binds accepted versions' is terse but functional, with no filler 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?

An output schema exists, so return values need no explanation, and the description covers pricing, the get_project precondition, and binding behavior. It omits quote lifetime/expiry and what max_credits=0 implies, which an agent invoking a cost-binding tool would benefit from knowing.

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% across four required parameters. The description only indirectly touches format ('MP3 or WAV') and hints at a cost ceiling that maps loosely to max_credits; project_id and, critically, idempotency_key are never explained despite being required, so the description does not compensate for the coverage gap.

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 ('Quote a finished MP3 or WAV') and makes the key property explicit: it prices the export 'without spending'. It separates quote from the implied prepare_export flow, though it never names the sibling that actually spends the credits.

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 precondition ('Existing ready downloads are free: check get_project first') and a clear condition under which the quote is free versus costs 5 credits. It stops short of naming the alternative tool (prepare_export) that consumes the quote, so routing is implied rather than stated.

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