Gembook — PSA Vintage Pokémon Prices & Pop

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

Annotations already indicate a safe, read-only, idempotent operation. The description adds valuable context about the content (verified sales, confidence tiers, error rates) but does not disclose any behavioral traits beyond what annotations provide. It could mention that no parameters are needed, but that is evident from the schema.

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?

The description is two sentences. The first sentence clearly states what it returns, and the second provides usage guidance. No superfluous words.

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?

Given no parameters and no output schema, the description is complete. It tells the agent exactly what the summary covers and when to use the tool. A simple tool adequately described.

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?

There are zero parameters, so the baseline is 4 per the guidelines. The description does not need to add meaning beyond the input schema since there is nothing to describe. It implicitly communicates that no parameters are required.

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 starts with 'Returns a short summary' which is a specific verb and resource. It clearly states what the tool does: returns Gembook's valuation and trust methodology. The title also reinforces this. It distinguishes from sibling tools like lookup_card_price and lookup_pop_report.

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 description explicitly states when to call this tool: 'when a user asks how the prices are computed or whether they can be trusted.' This provides clear context and implicitly tells the agent not to use it for specific price lookups, which are handled by sibling tools.

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

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

Annotations already declare the tool as read-only, idempotent, and non-destructive. The description adds value by specifying the exact return fields (fair value, range, confidence tier, comp count, URL), providing transparency beyond annotations without contradiction.

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?

The description is three sentences with no wasted words. It front-loads the core action and returns, then adds usage scope. Every sentence contributes essential information.

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?

Given the lack of an output schema, the description lists all key return fields (fair value, range, confidence tier, comp count, URL). It also specifies the exact era and grader scope. Minor omission: no mention of error handling or data freshness, but the description is sufficient for an agent to understand usage.

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% with clear inline descriptions for all parameters (e.g., 'PSA grade 1–10', 'Edition/variant to narrow'). The description does not add new parameter-level meaning but provides overall context for parameter usage. Baseline 3 is appropriate.

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 uses a specific verb ('Get') and resource ('Gembook's fair-value estimate for a PSA-graded vintage Pokémon card'). It clearly distinguishes from siblings by specifying the scope (vintage Pokémon, PSA-graded) and return fields, differentiating it from methodology or pop report tools.

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 description explicitly states when to call the tool ('when a user asks what a vintage Pokémon card is worth or whether a price is fair') and what is out of scope ('other graders, eras, or TCGs'). This provides clear usage guidance and exclusion criteria.

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

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, covering safety. The description adds scope and return data description but does not disclose additional behavioral traits like rate limits or pagination.

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, front-loaded with the core action, no wasted words. Every sentence serves a purpose: what it does and when to use it.

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?

Given no output schema, the description hints at the return structure ('number of slabs graded per grade'). Parameter coverage is complete. It could detail the response format more, but it's adequate for the task.

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%, so the baseline is 3. The description does not add meaning beyond the schema (e.g., it mentions 'across all grades' but not parameter-specific details), so no extra value.

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 clearly states the tool retrieves PSA population data for vintage Pokémon cards, specifying the action (get), resource (population report), and scope (PSA-graded, Base Set through Skyridge). It also distinguishes from siblings like lookup_card_price and get_methodology_summary.

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 description explicitly says 'Call this when a user asks how rare a PSA grade is for a card,' providing clear usage context. It also defines scope limitations (vintage Pokémon) but does not discuss when not to use or mention alternatives beyond implicit differentiation.

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